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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.
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.
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.
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
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
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.
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
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.
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".
It's like chasing a ghost.
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.
https://forums.edmunds.com/discussion/comment/5492957#Comment_5492957
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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/
One problem with this case is that it isn't one issue.
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.
2014 Malibu 2LT, 2015 Cruze 2LT,
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.
2014 Malibu 2LT, 2015 Cruze 2LT,
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.