Chevy Impala "REDUCED ENGINE POWER" message

thecardoc3 · April 2017

At one time P0121 was a throttle position sensor voltage code, on this car it is a throttle position sensor performance code based on the reported throttle position and comparing that to airflow calculations based on the MAF sensor, MAP sensor and engine rpm.

If the computer calculates that the reported airflow is too high when compared to the reported throttle position for .2 seconds (2/10ths) then this code will set and the result is a commanded limp in mode. Testing would have us take a serial data snap-shot during a failure and compare the related signals frame by frame for any discrepancies. Once the affected circuit is identified, then that sensor and it's circuit would be monitored with the digital oscilloscope to prove the exact reason for the signal error.

arshed_k · April 2017

2017 and I'm having the same problem. I have a 2010 Chevy Impala LT with 90k+ miles on it. I originally bought the car in 2011 used with 40k+ miles on it, so the car is no longer covered through warranty. Engine power reduced, service stabilitrac, etc. Here's the kicker and the following might be a little long:

I'm a full time college student, and a full time Uber driver. Last night I was with a passenger on I-94 heading towards O'Hare airport. My car reduced speed and suddenly dropped speed from 70mph down to 50mph. As I turned on the emergency light and start steering to the right to get onto the shoulder I was in the third lane to the right (the expressway is 4 lanes) as I was turning to the right to get onto the shoulder and to get to safety my steering locks, and there was a reckless driver going 100mph trying to cut off traffic. The lanes to the left were blocked so he had to cut me off by overtaking me by going onto the shoulder. He damaged his right rearview mirror and probably scrapped the right side of his car pulling off that reckless stunt. Had I delayed the breaking for a second I wouldn't be alive making this post today. Luckily I turned the car off, waited for a few minutes, turned the car back on and took the nearby Fullerton exit, and waited with my passenger at the nearby Target parking lot for the next Uber driver to pick up my passenger and get her safely to the airport. Had I not acted quickly, my Uber passenger would have missed her flight.

The sheer responses on this thread alone convinced me that my next car purchase won't be American. Hell, my brother who drives an 08 Honda Civic for Uber full time has 150k+ miles on it, and apart from basic maintenance repairs hasn't had anything remotely close to this happening to him, and he's been driving 2 years longer than I have. Had money not been an issue like in the past I would have taken this to the dealership where I got it to get it fixed, but I'm done paying tons of money out of pocket. This is the second time this has happened to me. The first time was about a year ago and I took it to a local mechanic and I'm not sure what he did. I was thinking of taking the car to Auto zone for a diagnostic before I take it to a mechanic, but after reading this thread it seems like a code sensor does not accurately diagnose the problem to pinpoint what exactly needs to be fixed.

Like I mentioned earlier, I drive Uber full time because when interviewing for jobs they don't coincide with my full time school schedule, hence why I drive full time. Everyday I'm not on the road makes it difficult to keep up. Hopefully I can get this issue resolved without paying an arm and a leg.

moose1a · May 2017

Found out The problem with the charging system is not the alternator or battery it is because The huminec Balancer Was bad

jes0011 · July 2017

Maybe we should make this go public i will be contacting the news channel cause i see we are not the only ones this has happened my family has almost died on the interstate because our service traction control engine power reduced came on and dropped my speed to 40 mph

mariagroth · July 2017

I had this problem with my 2008 chevy impala ls v6.

I scanned it and got a knock sensor code, and an accelerator code. Don't remember the numbers, sorry.

I took it to Purrfect Auto in Oceanside, CA and had the professionals there look into it.
They replaced the accelerator pedal, and the throttle position sensor for me.
That did the trick, now it's back to shape, haven't gotten the message again. Before it would hesitate or take a few seconds to pick up speed, but now it goes, in the words of Drake, 0 to 100 real quick.

For my knock sensor, that's a different problem for a different day... Lol. Hopefully this helps & you guys get your cars fixed. I'm surprised at how many people I see with this problem, GM should have a recall if they don't already.

jes0011 · July 2017

Spent $160 to find out it didn't fix the issue service traction power reduce light came back on yes let's take to another dealership and drop more money that some people don't have 2007 chevy impalas are a piece

d3s3rtboi · September 2017

So yesterday i got this reduced engine power display on this 2007 chevy impala i own and it happened on a moderate slope. Nothing crazy but the whole car gave out and in trying to get out of situation my car rolled back into a parked car in the parking lot i was trying to exit. Now have a ruined leftrear bumper and deformed left rear panel. This is not what id expect just put of no where. No warning just a surprise shut off all power no matter where or how fast the car is traveling and [non-permissible content removed] pray. Gm is not stupid this may be purposely inbuilt for cost and repair fees.

idriveapos · October 2017

I bought a 2007 Impala SS off the Show Room Floor it is the biggest hunk of junk I have ever bought It has cost me more in repairs than I have paid for it.new Tranny part number 17804091 many sets of tires due to chassis issues new Alt. part number J15139480 6 Batteries new Vent Solenoid Part number 20952523 and harness 19257603 Oil pressure sensor Part 12616646 and 11 dash actuators I have bought many new gm cars 1 Trail blazer 2000 3 C5 Vetts a 1973 Vette a 1980 Vette a 1984 Vette a 1992 vette a 1997 Vette and 2 2000 and a 2000 Tahoe a 1997 30th anv Camaro then this hunk of crap.more issues than all 12 new GM cars overs 35 years it now has the reduced power and Traction lights no power you all know the drill. I am now Disabled and on a fixed income which has made this even more pain full GM does not care for there customers anymore

idriveapos · October 2017

More from my POS driving in to our complex and the rear window rolls down on its own and will not go back up so have to jam a old golf glove in to the jam to keep it up and all the dash Actuators have gone bad a second time once again I will spread the word near and far about what crap[ cars GM builds and you better have the equal amount that you pay for 1 or more to keep it on the road. Just paid to my Reduced power issue fixed now this WHAT A POS the worst car company out there they put people in danger and do not give a [non-permissible content removed].

peter1961 · November 2017

Hi Folks;

First post, but I thought I would contribute to this forum that has been so helpful. My daughters car; 2010 Impala w/ 3.5 L has been going into (limp mode). Dash displays traction control and stabilitrac issues. This has happened to her at highway speeds as well as when starting the car after parking for some time.
I have personally witnessed one failure episode; I started the car, dash displayed warnings (above). Engine idled normally but the accelerator pedal had no effect (would not increase engine RPM). Next morning, all was fine but MIL light was on. My cheap code reader found P2122 ((Acelerator Pedal Position Sensor sw D low) and P2127 (sw E low).

I obtained the GM service manual schematic and determined that both the throttle body and APPS are connected directly to the ECM, inside the air intake filter housing. I disconnected the battery, removed the body support brace to remove the air intake top housing. Connectors on the ECM appeared perfectly dry and clean, as did connectors on the throttle body, Connectors were also inspected in the harness above the left fender (as mentioned by a GM service bulletin), and the connector on the infamous Accelerator Pedal.

After reconnecting everything, of course the codes are cleared and I can not get the problem to re-appear. Unfortunately the weather has warmed up, and I suspect that the subfreezing temps in the preceding days may have been a factor.
The Pedal (APPS) was removed and tested with a Fluke meter with 'bar graph'. The potentiometers seemed OK, there may have been a very slight 'jumpiness' in the change in resistance, as the pedal went through it's travel but I have nothing to compare it to.
I have order another pedal and will be installing it today, regardless. I have been a dedicated GM enthusiast for (I hate to say) 40 years! This problem is a life and death issue for family, and it is almost foolish to continue my love affair with Chevy, when these problems are not quickly and publicly resolved.

This forum has lead me to believe that the majority of the issues have been resolved by the Pedal replacement. I will post updates on the car's behavior in the following days and weeks. I am grateful for all the info I have found in this forum, hope that the results from my experience may help others.
Regards, Peter in Canada

Mr_Shiftright · November 2017

Great post, Peter and thanks for that. It seems like this issue with some GM products does have multiple causes, but certainly teting the APPS circuit is a good first step, especially if a corresponding code shows up. Certainly, as you say, electronics are temperature sensitive. In my experience, even just pulling apart and re-connecting a plug can correct an issue (although perhaps only temporarily).

peter1961 · November 2017

Hi again;
Here's an update on my daughter's 2010 Impala 3.5 L; Got a replacement APPS (pedal) on Monday, same day but wrong part! Today (Wednesday), finally received the correct part. I installed the part, this is literally a 3 minute job.
The "correct" part for this car is a Dorman 699-107. I might suggest a different after-market supplier, or an OEM part. The Dorman pedal seems to require about 25% travel before the engine RPM increases above idle. This is particularly disconcerting, given the problems we have had so far.
I called the Dorman toll free number as was told to check for pedal travel adjustments. Out came the pedal again! No adjustments were obvious and no instructions were supplied. Installation is really just two 10 mm hex head screws and a plug.
The car is running normally and I will be returning it to my daughter, although the weather has not been as cold as the preceding week that brought on this 'lack of throttle control' problem. Even if this pedal 'fixes' the problem, I may still be forced to replace the Dorman pedal with an AC Delco part, if she is concerned about the 'sluggish' feel of the new pedal.

I will report back, as some time passes, regarding the car's performance. Thanks again for all the valuable info in this Forum, regards, Peter

watsonk · November 2017

My 2008 Chevrolet Impala has 64,000 miles in it. My daughter was driving the car on highway and saw the Reduced Engine Power message, coupled with Check Engine Light on. After a few days, my daughter reported that both message and warning light had turned off on their own.
I remembered that I had received a recall notice about Throttle Body (with similar message) from GM a few years ago.
When I took the car into dealership this morning, the dealer said that it was caused by a malfunction Gas (or Accelerator) Pedal Sensor and was not covered under the recall. The repair cost was almost $350.00.
In my opinion, both the Gas Pedal Sensor and Throttle Body should be in the recall because they cause the same symptoms.

Mr_Shiftright · November 2017

That's correct. There is no "one solution" to this problem.

peter1961 · December 2017

Hi Folks; Another update on my daughter's 2010 Impala 3.5L:
It's been 4 weeks since I replaced the Accelerator Pedal and so far, all is fine. We have had some even colder weather than the conditions at the time this started regularly acting up.

I hesitate to say it's fixed, with my luck, I'll jinx it! But......it went from malfunctioning a couple of times a week, to zero failures in 4 weeks. I am going to wait another month or so, and then disassemble the old Accelerator Peddle Position Sensor. I am curious to see if there are any signs of trouble on the actual rheostat. Disassembly will likely be a 'one way' process, so I want to be (even more) sure the problem is not elsewhere.

I will keep you posted. Thanks to all who have contributed to this thread. I have likely saved numerous large repair bills and reduced the dangerous condition that the vehicle has put my daughter in.
Merry Christmas and Happy New Year, Peter in Hillsdale, Canada

Mr_Shiftright · December 2017

That would be interesting, to disassemble the APPS!

jbbailey · December 2017

I have a 2008 chevy impalla ss. Here recently as soon as i start my car the service stabiltrack service traction control and reduced engine power indicators all come on simultaneously. I cant drive 15 ft without it doing it. The first time i experienced it i was on the highway going 70mph and all of a sudden i was dropped down to 15mph within a few seconds. The car behind me literally ran off the rd to avoid plowing into the back of me. I am livid. Ive owned chevrolets since my first silverado at 17. But i think this is it for me. For what ive been told it can be a number of things including my throttle body. I need help guys, ive lost my job because of my lack of transportation. Wheres the recall Chevrolet??

dillissen52 · December 2017

I have a 2011 Silverado. First time trouble was a dead battery for no apparent reason. Then about a month ago while driving, the door locks went crazy lock, unlock,lock, unlock, reduced power and every idiot light on the dash was on. Limped to the side of the road and the truck cleared itself. carried on until 2 days ago, Service traction lights on and flashing and service engine light is on. This truck only has 78,000. k on it and I am kicking myself for not keeping my F150. I am in BC (Maple Ridge) my town does not have a GM dealer so now I'm to risk my life to get it to a GM dealer out of town???

Mr_Shiftright · December 2017

You still might be having battery/charging issues. It's always the first thing to check when the electrics go crazy. Also the ground cables, battery-to-frame, and engine-to-frame.

colleen_r1 · March 2018

My daughter was driving our 2009 Chevy Impala 3.5 L (129,000 mi) on the highway 2 weeks ago when the speedometer dropped to 0 and the steering wheel locked up and engine power reduced message displayed. Thankfully she was able to pull over without causing an accident. After a few tries the car restarted. She took it to the local Chevy dealership and they replaced the APP sensor and speed harness to the tune of $800. After finding this discussion board, I inquired about a recall and was told there was none. I can't believe with this well-documented problem going back 8 years there isn't one! How do we get the attention of the NTSB?

navypinoy88 · April 2018

Had similar issue, popped the hood 4 wires all broke coming from the sensor to the engine. Harness felt very brittle on a 2008 chevy with 150k miles. Could be something as small as 1 wire broke in that harness causing problems for you guys. With the wiring underneathe the hard shielding its hard to see and alot of mechanics first step is throw parts at a job to see if it fixes it them read wires first. Do your research open things up visual inspections can tell you a lot. If I take my car to a mechanic or dealership or whatever the case may be ill tear into the problem myself . your going to get charged out the wa-zoo so might as well make them work for your buck lol

navypinoy88 · April 2018

And the wire repair fixed the issue forgot to put that in there easy fix

thecardoc3 · April 2018

@navypinoy88 Did you ever hear of the law of unintended consequences?

navypinoy88 said:
Had similar issue, popped the hood 4 wires all broke coming from the sensor to the engine.

The sensor? That's not much to go on in the when looking under the hood of today's cars.

navypinoy88 said:

Harness felt very brittle on a 2008 chevy with 150k miles. Could be something as small as 1 wire broke in that harness causing problems for you guys. With the wiring underneathe the hard shielding its hard to see and alot of mechanics first step is throw parts at a job to see if it fixes it them read wires first.

You should know that top technicians across the country DO NOT throw parts first. Learning to take a disciplined repeatable sceintific approach takes time especially when doing so goes against what many consumers want, which is fast and cheap. They don't worry about right the first time until they don't get it.

navypinoy88 said:

Do your research open things up visual inspections can tell you a lot. If I take my car to a mechanic or dealership or whatever the case may be ill tear into the problem myself . your going to get charged out the wa-zoo so might as well make them work for your buck lol

Here is where the unitended consequences are. With a steady flow of work a young technician can have a steady career plan and he/she will over time learn the right way to approach every problem and learn to get it right the first time, everytime. Without that steady workload which is a share of harder as well as easier tasks the technicians overall experience has more holes and it takes longer for them to become seasoned. In fact it can take such a long time that they may struggle to earn a reasonable standard of living as a technician so they quit before they really master the trade. If you think auto repair is expensive now, just wait until there are no technicians to repair broken cars. Then when something goes wrong with your car and you can't fix it, it will be a worthless throw away and you can just spend another 30K (or 40K?, 50K?) on a new one. I hope you'll be able to keep laughing when that day comes.

ozziez1135 · April 2018

Well this is nice to see after 8+ years of this post going that there is not a definite solution. I have a 2009 impala that i am stuck with and need to continue to make payments for the next 2.5 years, and i cant drive more the a mile at a time without this issue. When it 1st started to happen i replaced the throttle body and did the relearn for the rpm. Everything seemed fine for a few weeks, then it started all over again. At 1st it was once a week, but today its happened 4xs (literally every time i got into my car) I purchased through a dealership who sucks at everything they do and every time i get my car back from them there is something else that needs to be fixed (last time was the bumper, got a huge dent in it that i didn't notice til the next day and have no way to prove it.. of course) But when i bring it to them they are saying this ISN'T covered under warranty (even though i got the bumper to bumper 3 yr extended one) so now im stuck with the option of have a broken car that im paying on, or dump a bunch of money into a car that im paying on that may not even fix the issue leaving me out more money that i truly cannot afford to spend. I have gone through all 23 pages of comments in here, and nowhere in here is there a definitive solution... WTF GM?!?!? Please someone help? i need a solution to this issue that seems to be VERY common. Someone must know what to do to get this solved once and for all....

thecardoc3 · April 2018

ozziez1135 said:
I have gone through all 23 pages of comments in here, and nowhere in here is there a definitive solution... WTF GM?!?!? Please someone help? i need a solution to this issue that seems to be VERY common. Someone must know what to do to get this solved once and for all....

There is a definitive solution for each possible failure. Someone with the right tools, training and experience just has to take the time and prove what is causing the issue with your car.

captinbandwagn · April 2018

Sept 2016 - while driving a 2011 Chevy Impala with 60,000 miles at 65 mph on 4 lane highway I get the service stabilitack and Engine Operating at Reduced Power messages. Car still running fine so I kept going to reach an exit. After 10 minutes, just before the exit, the car LOST ALL POWER; no power steering, no power brakes, no lights, no engine power at all either! So I was able to coast up the exit ramp. After engine cooled we were able to drive home 20 miles. Ended up replacing the throttle body myself. $200 and servers bolts, actually an easy fix anyone can do. Don’t take to a shop and pay $600 for this easy to do repair.
APRIL 2018 - engine operating at reduced power message again! I pulled into a parking lot right away and left engine cool 1/2 hr and was able to drive home.
CAUSE: I think this is an engine design flaw. The throttle position sensor in the throttle body is directly above the exhaust manifold that gets 400-500-600 degrees Fahrenheit. So the electronic sensor in the throttle body fails after being exposed to this tremendous heat over and over. If they used a cable from the throttle to the gas pedal, this issue would vanish.

Mr_Shiftright · April 2018

That's an interesting theory. I wonder, though, if you aren't focusing too much on the throttle body as the sole possibility. As we've found out, there's really no such "thing" as a Stabilitrak--it's a series of components within a system, and so every component in that system is suspect. It's possible that replacing the throttle body cured the symptom but not the disease.

The only surefire way to get to the bottom of failures like this is to carefully test each component at the time of failure, to see what is failing or what is/isn't "talking to each other".

captinbandwagn · April 2018

If operating at reduced power initiates, it is logical that Stabilitrac and Traction control would have their power cut off first as they are unnecessary, and why they come on the car messages as being turned off along with the reduced engine power message and the check engine light came on. That is exactly what happened to me twice. Then after the engine cools, the messages vanish, the check engine light turns off and the cars like nothing happened. After I changed out the throttle body which included the electronic position sensor, my impala ran fine for the next 18 months.

Mr_Shiftright · April 2018

Well yes I understand, and you may be perfectly correct in your particular case. But there are many instances of new throttle bodies having no effect on this problem. Some say "harness issues", some say Pedal Positioning Sensor, and others refer to various other components of the system being at fault.

It's like chasing a ghost.

radtad67 · April 2018

I have a 2004 impala....which where ever I look there is one so I chase them down and they are having the same problems but can' afford anything else so they are driving it til they quit. I'm having ABS and traction control system then at the same time went to park the piece of Canada crap...which how can u say it made is the us...I don' care who owns it and where it's at....and it wouldn't go in reverse for 3 seconds....then (((crash))) front end jumps ....must be in now...so I gas it and parked it and that is' where it sets. Now people we need to stick together and start this class action suit against gm. Cause we can't by anything but American. Ya right this whole thing makes me sick. My car just turn 110k wtfgm..I guess they are making cars like bic lights....when they are out of gas Chuck them.....I don' think so...to much money for me to throw away. I'm calling my lawyer tmrw cause there is way to many cars with the same problems. It's time gm did there job...we did ours and bought the piles of [non-permissible content removed]. Now turn them back into something we are proud to own!!!!!

bushwhacker2 · April 2018

I have a security patrol company operating in four4 counties of northern California. We had Chevrolet Luminas with the 3.1 engines for ten years and never had this problem of "Reduced Engine Output'." Now with Impalas with the 3.5 engine, all are 08 -10 models with between 70,000 and 160,000 miles, half our fleet have this problem and following diagnostic evaluation and expensive repairs, none have been fixed. We use them in congested areas where 5-20mph is all that is required. The cure for us was to cut our losses and buy foreign because we put two thousand into each car for light bars, spot lights, lettering etc and cannot just send them to the wrecking yard? Going now to Toyotas, we are having few problems and when one occurs it is normally fixed at no cost to us.

captinbandwagn · May 2018

This has happened to me three (3) times now. The "engine operating at reduced power" while driving and loss of stabiltrac and loss of traction control. 18 months apart.and then the very next day.
The first time, 15 min after that message appeared, the car powered off; I had No power brakes, No power steering, No lights. If you pull off and let the engine cool, you can drive it again and the reduced engine power code goes away (until it happens again the next day), so No need to panic and call a tow truck. Twice fixed with a new throttle body assembly (comes with throttle position sensor) costs around $150 at a parts store and is super easy to install and only took 10 minutes. Be sure to disconnect the battery to clear the engine codes. I still firmly believe this is a GM engine design flaw. The throttle position sensor is electronic and sits 4" above the exhaust manifold that must get to 800 degrees. ( says online they can reach 1,200 degrees) This intense heat must wear out the electronic sensor in the throttle body. Has anyone tried to shield the sensor from the heat? I guess to be safe, this throttle body will need replaced at every other oil change.

radtad67 · May 2018

ATTENTION CHEVY IMPALA OWNERS WITH BAD TRANSMISSIONS....FIRST CALL GM AT 1-877-558-8352 TO START A CASE AND SCHEDULE A SERVICE CHECK ON THE TRANSMISSION. DO NOT LEAVE THE CARS SIDE THEY ARE PROTECTING GM. THEN FILE A CASE WITH NHTSA AT 240-247-0015. YOU CAN DO ONE RIGHT AFTER ANOTHER. JUST EXPLAIN WHAT IS WRONG WITH YOUR CAR AND TAKE AS MANY PICTURES AND VIDEOS YOU CAN.

radtad67 · May 2018

THIS SITE IS NOT SAFE TO EXPLAIN YOUR ISSUES.....THEY REMOVED MY PICTURES OF THE PARTS THAT CAME OUT OF MY TRANSMISSION IN MY FINE PIECE OF SH*T IMPALA. IF THIS IS A SITE FOR ISSUES WITH OUR CARS WHY IS STUFF BEING TAKEN DOWN?? ANY PROBLEMS WITH YOUR CARS GOT TO NHTSA AND YOUR MAKE HEADQUARTERS FOR FILING A CASE...

kyfdx · May 2018

radtad67 said:
THIS SITE IS NOT SAFE TO EXPLAIN YOUR ISSUES.....THEY REMOVED MY PICTURES OF THE PARTS THAT CAME OUT OF MY TRANSMISSION IN MY FINE PIECE OF SH*T IMPALA. IF THIS IS A SITE FOR ISSUES WITH OUR CARS WHY IS STUFF BEING TAKEN DOWN?? ANY PROBLEMS WITH YOUR CARS GOT TO NHTSA AND YOUR MAKE HEADQUARTERS FOR FILING A CASE...

Your pictures are right here, where you posted them:
https://forums.edmunds.com/discussion/comment/5492957#Comment_5492957

If you don't want your posts taken down, then watch your language. This is a family friendly forum.

Thanks!

sheena83 · July 2018

I have a 2013 Impala LT the engine light is on reduce power saver comes on stabilitrack control comes on. I have had the pedal changed, the trottle body changed, a fuel flush and nothing has work. I have taken it to a dealership, to a backyard machanic, and even googled the problem, but nothing is working. This is costing me a lot of money and it’s very frustrating. Can someone please help me.

Mr_Shiftright · July 2018

Go to THIS WEBSITE, click on "repair shops" and see if, hopefully, there is one on the list that is reasonably near you.

These are considered among the best trained auto techs in the business. There is no reason why this problem cannot be fixed.

http://www.iatn.net/

Judith Schoen · August 2018

I have the same problem on my 2011 impala, took it to Midas. They found the history code for the reduce engine power. They are now testing the gas pedal assembly to find out what is going on . Really haven't had any major problems with car. Have had the car 5 yrs, just replaced battery last year, motor on wipers twice and a front wheel hub. Don't trust dealership.

Jessicab360 · August 2018

Is anyone interested in looking into a class action here? Seems like so many people have this issue, but GM hasn’t recalled it.

Mr_Shiftright · September 2018

Generally class action lawsuits aren't a big payday for the car owner, in most cases. You'd be lucky, after years of effort, to end up with a couple hundred bucks. The lawyers do a lot better.

One problem with this case is that it isn't one issue.

Hotblonde57 · September 2018

I have a 2001 Chevy Impala less than 50000 miles the other night coming home after dark road construction and all of a sudden car started loosing power idiot light that looked like a battery csme on seconds later as i was turning acrosd higheay drad no power no liight..I had a flashlight in purse waved at oncoming traffic praying not to be ran over.this went on for 30 min. I tried again it stsstar so I floored it the next seven miles home through red lights curveds etc. Lost it when home. Cried for an hour.had friend check battery fine alrenator fine car starts he said can't disgnose problem or fix till it's having one. I'm terrified it Will Occur again might not be so lucky. I travel alone alot busy and desolate roads.the only recall I have is to get the ignition key module checked.what should I do about thid issue. I'm recently widowed. Already have financial issues from unexpected death bills etc. Working as a model and a medical Coder barely making it. Cannot afford what if at dealership or repair shop and can't afford another vehicle.this one just purchased less than yesterday ago. Please someone help me.thanks (e-mail deleted by Host for privacy purposes)

imidazol97 · September 2018

The fact stated that the battery light came on indicates to me that the computers thought the car lost battery power. No lights after the car stopped does the same.

The battery itself should be replaced or substituted with a known good battery--such as switching with the battery in another vehicle. The battery may have an internal short, especially if it's more than 4 years old.

A friend who checked the battery for you might have a vehicle with a similar battery with the positive and negative connects on the same ends that could trade batteries with you. HOWEVER, a good battery test by a unit that puts a load on the battery and checks for sulfation as well is what's needed here. The test unit can determine how much of the ability to provide current is left in the battery: that's a way of determining how much life is left in the battery.

The connections from the battery to the connections should be loosened, cleaned and reconnected. That applies to the negative cables that go to grounds. Same for the positive cables and their connections.

The connectors that go into the vehicle through the firewall should be unsnapped, inspected, and reattached.

The ends of the cables at the batteries should be inspected by cutting into the plastic covering to be sure the copper wires inside are intact.

I wonder how old the battery is. A car with low mileage at 17 years of age, may have a battery that's been in there a long time.

Best of luck at tracing this down.

thecardoc3 · September 2018

Those cars are known to have ignition switch issues and it's pretty easy to prove when it acts up. All you need to do is use a volt meter and measure the voltage on fuses in the fuse block at the drivers end of the dash. Some of the fuses are powered all of the time, so they would show you the battery voltage. Others are powered via the ignition switch and they should be within a .1 -.2v of the power you measure at the fuses powered directly by the battery. Normal battery voltage should be 12.4 to 12.7volts.

Now to test, start the car and let it run for about how long you drove it the other night with all of the accessories on. If the switch is heating up and losing the connection you should see the voltage starting to drop on specific fuses. Share this with your friend. I can give you more details if need be.

imidazol97 · September 2018

How does total loss of power to the lights fit in with the ignition switch problems?

thecardoc3 · September 2018

The exact answer would depend on exactly what groups of fuses have power during a failure event and which ones do not. I'd have to upload a power distribution schematic to show you what I mean by that but there is more than one power source to the ignition switch and more than one output from it. Some of the inputs to the switch also directly power fuses in the fuse block. The combinations of where there is and is not power lead to the best choices to choose the next step in the testing.

Now what may seem a little confusing at the moment is how she is describing the failure "all of a sudden car started loosing power idiot light that looked like a battery csme on seconds later as i was turning acrosd higheay drad no power no liight." I interpret that as the vehicle stalled and there were no warning lights on the dash. That would be a classic description of the ignition switch losing its connection.

Warmacht9 · September 2018

pooh07 said:

my car is displsying engine power reduced, any suggestions for the problem?

yes it's your throttle body sensor and anybody needs to go to Walmart for $39 and buy a car diagnostic and code reader it's one little machine you can update it online it's great it has saved me so much money with mechanics lying to me over what is wrong with my car it's not

Warmacht9 · September 2018

Hotblonde57 said:

I have a 2001 Chevy Impala less than 50000 miles the other night coming home after dark road construction and all of a sudden car started loosing power idiot light that looked like a battery csme on seconds later as i was turning acrosd higheay drad no power no liight..I had a flashlight in purse waved at oncoming traffic praying not to be ran over.this went on for 30 min. I tried again it stsstar so I floored it the next seven miles home through red lights curveds etc. Lost it when home. Cried for an hour.had friend check battery fine alrenator fine car starts he said can't disgnose problem or fix till it's having one. I'm terrified it Will Occur again might not be so lucky. I travel alone alot busy and desolate roads.the only recall I have is to get the ignition key module checked.what should I do about thid issue. I'm recently widowed. Already have financial issues from unexpected death bills etc. Working as a model and a medical Coder barely making it. Cannot afford what if at dealership or repair shop and can't afford another vehicle.this one just purchased less than yesterday ago. Please someone help me.thanks (e-mail deleted by Host for privacy purposes)

I was told the same thing can't diagnose it until it is happening everyone get you a car diagnostic and code reader at Walmart for $39

mj247 · November 2018

I have a chevy impala 2008, I love this car, when the car is at its best the performance is wonderful. But the headache with the bs to get the car repaired leaves me very agitated beyond words. Yes currently the car is 10 years old and I am dealing with the reduce engine power, it was/ is a major safety issue and almost caused a serious accident, liability is a great word that comes to mind and thanks to this forum I have over 100- 200 customers with the same problem that make well for a class action lawsuit independent of the recall that was provided via GM because there was no mention of the chevy impala on the list. i hope that other customer join in and make GM pay for all the risk that we have encountered with this car and the customer service or the lack there of. We as well as our families lives are at risk...it is of no wonder that the production of this car is at a cease. I have empathy for everyone that make a living with this company. I dont think that I would be hard press to say that the exes of GM dont drive the car that they produce, heaven forbid that their love ones and family experience any of these issue.

Chips70 · December 2018

Try the throttle position sensor

ZachG · February 2019

idahofarmboy said:

Somebody please help me. I have an 07 chevy impala that keeps giving me a "reduced engine power" message, then cuts your power and you can't drive more than about 40 mph.. I took it to a local mechanic and he said that it was a corroded sensor, that was in the air cleaner. He said that he fixed it and set us on our way. A few days later it did it again. It has no pattern, you can be driving uphill, downhill, or on the flat, and at any speed. It is happening more frequently. Anybody else had this problem. I can't see that there is a recall and I can't think that I am alone on this. I really don't want to take to a dealer, they can be such a rip-off, not to metion the closest one is 1 1/2 hours away. Thanks See Also: 2011 Chevy Impala - Service Stabilitrak - Reduced Engine Power

My girlfriend had this problem with her 2008 Chevy impala. It was shooting two check engine light codes, low power mode and some other lights. She experienced the car shutting down on the highway. I take a look at the codes and to fix the problem. I had to replace the throttle body for the one check engine code and the accelerator pedal sensor. That got rid of the low power mode and the codes. The low power mode could be caused by any of the wiring or sensors going into the throttle body or the plastic pipe between the throttle body and the air filter. For anyone doing this themselves go on rockauto.com the parts are cheap. Throttle body was around $70 and the sensor was around $30.

Chevy Impala "REDUCED ENGINE POWER" message

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