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Chevy Impala "REDUCED ENGINE POWER" message

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  • gmcustsvcgmcustsvc Posts: 4,113
    kdh12389,

    We're sorry to hear that you are experiencing this concern and can understand how it's a frightening experience. If we can check into this further, please contact us at socialmedia@gm.com with more details (including your name and contact information, the last 8 digits of your VIN and mileage, and a recap of the situation so far).

    Sarah, GM Customer Service
  • trumble09trumble09 Posts: 13
    edited January 2013
    I was driving my 2009 Chevy Impala on the highway in a snowstorm and received the dreaded Service Traction Control/Reduced Engine Power messages and my car went from approximately 45 mph down to 20 mph and sounded like it was about to kick the bucket. I logged on here and started freaking out seeing people had spent $$$$$ to fix it, My father contacted a family friend who is a GM certified Mechanic and explained the problem... he said its pretty common. Anyways he told him to look at the "Drive by wire" wires going into the Throttle body, sure enough one of the wires was pulled loose from the plug not getting a solid contact and causing a short. With the car running (like garbage on reduced engine power) he pushed this loose wire back into its plug and magically the car immediately began to run like normal. All that's required is to buy a new "throttle body wire harness" which runs for 80$ on car parts discount websites, or trim back the wire insulation and solder the connection back in place. Seems to me from the fixes people posted its either the gas pedal or this wiring harness. To those who have tried the gas pedal replacement and continue to have problems check this wire harness that plugs into the throttle body. Here's a video from Youtube, I know this is a pickup truck but its the same issue, same wire harness, and in the same location under the hood of the Impala.

    Loose Throttle Body Harness Wire Fix
  • jfudgejfudge Posts: 2
    I have a 2009 Impala with same symptoms and after reading pages and pages of people having this same problem I am amazed. This obviously is an issue that should not be happening at this early age of my vehicle.

    This is my last Chevy, too.
  • The sad part is I have been dealing with the customes service (like I was asked to) and I have gotten NO WHERE! Trumble09.. my car says "starter disabled service throttle" before I get the "engine powee reduced" message. The car completely dies. I have to get out and take the terminal off to restart it. GMs advise to me was take it to a GM mechanic. The last GM mechanic that worked on my car somehow managed to put antifreeze in the transmission fluid.. I have 2 kids and I'm in college, I don't have the time or money to pay them to tell me they can't figure it out. I absolutely love this car when it's running but after all of this I will NEVER buy another Chevrolet.
  • trumble09trumble09 Posts: 13
    edited January 2013
    Hey sorry I forgot to include that my car also displayed "service throttle starter disabled"after I turned my car off when it had been running rough. Ill take a picture of the wire harness and post pictures on where to find it. Give me an hour or so I'm replying from my phone at work. All in all its a p!ss poor design that's prone to failure. Before paying for a gas pedal try this throttle body wire harness as it may be the culprit.
  • trumble09trumble09 Posts: 13
    edited January 2013
    Throttle Body wire harness pictures:

    So this is the establishing shot, once you have popped the hood this is what it should look like more or less, pardon the dirt and sand its wintertime here, also pardon the picture quality its currently -4 degrees fahrenheit with a windchill making it -7.

    This red circle is the area you're going to be concerned with, you can leave the valve cover on if you like. if you wanna take it off it involves unscrewing the oil cap and removing the oil cap fill neck and giving the plastic a tug. Instructions can be found on google

    Engine shot

    This next picture is of the drivers side front portion of the engine, the bunch of wires circled in red are the throttle body wire harness, Grip these wires in your hand and push them towards the plug and any loose connection that may be present will re-establish and either your motor will be back to running like normal or else this isn't the problem... but this is a good check to do before you go to the dealer and throw money at them to try to fix your car, if it's not this bunch of wires chances are its either the throttle body itself, or the APPS sensor in the gas pedal

    Harness close up

    Hopefully this helps some people, if your car is still running like garbage after having the dealer replace the throttle body and gas pedal check this bunch of wires because this wire harness is not often replaced when the throttle body is serviced.
  • Yeah if your problem is caused by the exact same thing then Chevy needs to re-evaluate their wire/plug design. I had an issue with the airbag wire harness under my passenger seat 2 weeks after I bought my car, took it to the dealer took them all of 5 minutes to diagnose and i was charged 60$ because wires and sensors weren't covered by warranty. they just shoved the wire towards the plug and called it good 'nuff. check my post below with the links to pictures on Flickr and see if it helps your car, my car the minute that wire got shoved back into place was night and day as far as running like it should and not in the reduced engine power mode. Also works if you try to start the car and get the "Service throttle, Starter Disabled" message
  • Sorry KDH, forgot you have the SS, probably the LS4 motor, I found a picture of one and circled and arrowed to what I believe is the Throttle Body Harness, not positive though you may know more about where the throttle body is on your v8

    Impala SS Wire Harness
  • Ive been dealing with this since my car was practically new; only in the winter. I had in in several times under the warranty and they did nothing. Its really cold now and this is getting dangerous. I saw this post and so I jiggled and pushed those wires. It drove like a charm for 30 minutes. Then it went bad. Usually I can stop and wait a while and then go futher. I have appointment with dealer because I complained that they never fixed it but now at over 10000 miles they will cerainly charge me no matter how much I complain. I was hoping I had fixed it myself. Im a woman and am my wits end with this. I mean I had it in under the warranty and extended warranty so many times. The pedal was replaced (by me) and they cleaned the throttle or something.
  • As soon as my husband watched the video you sent me a link of yesterday he went out and jiggled all the wires with no change. The only time my car doesnt shut off is when u have ur foot completely buried in the throttle. But as soon as u let out of it it dies. I just want someone to tell me what the problem is so i can fix it myself. Anymore ideas??
  • gmcustsvcgmcustsvc Posts: 4,113
    Do you already have a plan of action for getting this checked into, jfudge? Let us know if you decide to work with a dealership as we're available to assist in that process.

    Sarah, GM Customer Service
  • trumble09trumble09 Posts: 13
    edited January 2013
    If you jiggled the wires and it ran perfectly it would seem this is the problem. Jiggling isn't a permanent fix, it allows you to self diagnose before paying beacoup bucks to have the dealer "diagnose" that you need 500$ worth of reprepair. You have 1 of 2 options. 1. Take it to the dealer show them the wire harness and have them replace it, GM charges customers 180$ for the part plus whatever labor the garage sees fit to charge. 2. Find someone with pretty basic electrical repair knowledge show them the wires tell them one has a broken connection and needs to be re-soldered and pay them whatever they charge for wire repair which won't be nearly as much as the wireharness repair bill from the dealer. Look at the youtube video "throttle body harness wire" I linked to up a few posts to see how to disconnect the wire from the terminal to re-solder it.
  • trumble09trumble09 Posts: 13
    edited January 2013
    My only other 2 suggestions are to disconnect the gas pedal and inspect that terminal and those wires for corrosion or damage. If that seems to be fine then you could possibly try to clean the throttle body there's a part called a butterfly its basically a metal disk with a rod through the center that opens when you put the throttle on and closes when you take it off, this can become gunked up and require cleaning with throttle body cleaner. Have your husband Google it and see if either of these problems may be the cause, sorry the wire jiggle didn't turn out to be the issue. =(

    P.S. try the wire jiggle on the gas pedal terminal too as one of these wires could be loose.
  • I drive an impala SS 2010 with only 59,000 Last night while driving on the freeway my check stabilitrack, check traction control and then the reducing engine power came on my dashboard. I was able to drive the car off the free way but am not sure if I should continue to drive it anywhere else(a mechanic). I did notice a slight tug while I was driving but also know I am due for an oil change. I have read about gas petals and sensors being off. I have already replaced 5 sensors since I got it so this would not come as a shocker. I have had nothing but problems with this car but as a girl living by herself in a new city does anyone have any suggestions????
  • I am not a mechanic but everything I've read online and heard from my dealership is that you are still able to drive the car when these errors appear. You do want to get it into the shop asap but you can drive it there rather than getting it towed. I had this problem with my 2011 malibu which is out of warranty and the dealership fixed it for nothing because they know that GM is having issues with the throttle body. I also have a co-worker who owns a 2008 Impala with 50,000 miles and this happened to her last week - same error messages you are seeing. She drove straight to a local dealership armed with the information that MANY GM's are having this issue and there were no questions asked, she got it fixed for nothing. They didn't even charge her the diagnostic fee. If I were you, I would go to or even call the nearest dealership and see what they are willing to do for you. It seems as though most of them are being pretty reasonable in dealing with customers who have this problem.
  • The throttle body is no longer covered under the powertrain warranty as of 2010. They must have been spending too much money on throttle bodies so they quit covering them. I have a 2011 Impala with a similar problem, code P2135. The car has 53K so the real warranty has expired. The dealership wants around $500 to replace the throttle body. I can buy the part on ebay for $130 and take a half hour of my time to replace it. It's upsetting that Chevrolet extended the throttle body warranty on the trucks for the same problem but not the cars. Good job GM.
  • gmcustsvcgmcustsvc Posts: 4,113
    shesok2010,
    If you want for us to get you more information about any applicable warranties or to assist with working with a dealership to get this checked into, please email us at socialmedia@gm.com with more details (including your name and contact information, the last 8 digits of your VIN and mileage, and a summary of the situation).
    Sarah, GM Customer Service
  • trumble09trumble09 Posts: 13
    edited January 2013
    I experienced the same thing with my 2009 Impala LS, I had it narrowed down to a throttle body wire harness since juggling it would make it start and run right, turns out it was the pins that those wires were connected to in the electronic portion of the throttle body, I continued to drive it with no problems except occasionally getting a message that the throttle was disabled and the car wouldn't start but wiggling the wires worked. Last night however my car wouldn't start and I killed the battery cranking it over and trying to clear it with an Actron code reader, I had it towed after much hassle because the company sent a truck that wouldn't fit in the low clearance garage, I called the dealership I had it sent to explained the problem and informed them that while the battery was dead this wasn't the issue. they performed the diagnostic and found codes pointing to the throttle position sensor and knock sensor and replaced the throttle body with no hassle, I will be picking it up from the dealer tomorrow morning. I have heard estimates of it being costly, I've found replacement throttle bodies online for 130-150$
  • gmcustsvcgmcustsvc Posts: 4,113
    It looks like you'll be tackling the throttle body work on your own, trumble09 - hopefully things go well!

    Sarah, GM Customer Service
  • No, I took it to the dealer as it was covered under warranty, they replaced the throttle body electronic portion not the part containing the butterfly and said the car ran like a charm when they test drove for 20 miles, My father went to go pick up my car from the dealer, got in turned the key over and wouldnt start at first then it turned over and it immediately began running rough and displayed the "Engine Power Reduced" message. It seems like the technicians are stumped, as it was giving code p2135 which indicated a throttle position sensor and having replaced those it is still displaying the message, I'd rather not pay to have them guess what the possible cause could be, in the past I've been nothing but happy with their service, but for them to not know why my car is displaying this message is frustrating to say the least...
  • gmcustsvcgmcustsvc Posts: 4,113
    Sorry for my misunderstanding!

    If you want for us to check into this further, if for nothing else than further documentation, please don't hesitate to contact us at socialmedia@gm.com (include your name and contact information, the last 8 digits of your VIN and mileage, and a summary of the situation).

    Sarah, GM Customer Service
  • My 2008 outlook 8J118867 has left me stranded twice this last week. I get a computer message of traction control off and much reduced power. Out of desperation I have discovered if I turn off the car, it can “reset” itself and go back into drive mode with a check engine signal. The codes given are:
    P1516 Electronic throttle mod VS, Throttle Position Performance
    P2119 Throttle Closed Position Performance
    P2135 TP Sensor 1-2 Correlation
    It needs to be fixed quickly as I live in a mountainous area and I literally “get stuck” with my two young girls.

    My trusted mechanic owns Sabaru here in Colorado springs. We have not had the best of luck going to dealers here and in Denver. We had transmission replaced when we were stranded near Denver and had to push car off the road (literally). It was amazing that it was replaced “no questions asked’ and the dealer there admitted they had to replace “a lot”. That told us that the car brand was having lots of problems.

    Our local dealership is: Mike Shaw GM 1313 Motor City Dr 719-636-3881. This is the same place that argued with us about our headlight problems and then after we paid to have them fixed at a cheaper shop, a month later the recall went out about the light connectors.

    Right now it is sitting at Sabaru Repair (they have been AWESOME on our subarus and I trust them totally) and Martin and I are researching the problem – and I came upon this website.
    Please let us know what GM is doing about this problem. Thank you-
    Brenda S
  • gmcustsvcgmcustsvc Posts: 4,113
    Looking at your VIN, outlook2008, your powertrain warranty expires today (unless you're mileage is already past 100,420 MI). I understand you have a good relationship with your mechanic, but if you had wanted to see if what's happening with your vehicle would be covered it would be better to act on that sooner rather than later.

    Sarah, GM Customer Service
  • hi. i have a 2010 chevy impala. they are GARBAGE. service light came on when i left chevy dealer ship. they are saying nothing they can do since i left their property. i have no service warranties they say.. i was sold garbage. now i get the same message everyone is getting service traction control engine powering down. i was driving 2 days ago and it came on i went to pull over to shut vehicle off. it seems to work for a bit. as i went to turn. steering locked brakes and gas peddle went stiff. i had no control of the car went into opposing lane. and stopped. that scared the living day lights out of me. i could have been killed. i dont know what to do. i need help.. i drive granddaughter back and fourth and scared to dealth only vehicle i have. i need it for job. i only had this garbage a yr and half. nothing but headached. will NEVER BUY A NOTHER CHEVY AGAIN. THOSE PPL SHOULD BE SUED.
  • Funny story, Dealership diagnosed my car as having a bad throttle body, replaced it, still got the p2135 throttle position sensor error, dealership was stumped and said anymore poking around would start costing me money. so My dad said I'll be there to pick it up. While he was there, he picked up a wiring diagram for the throttle body harness to check ourselves since it doesn't cost us 60-100$ an hour whatever labor cost is these days. He voltage tested two wires in the harness i don't know which but the voltage was 11 almost 12 volts, which is full battery voltage... that's a lot higher than normal 4.5ish or something I read it should be... so the garage suggested I get a new battery, I had the original AC Delco battery that came with the car so it's 4-5 years old, we have a spare lying around we connected the spare and the voltage dropped to normal levels. So fingers crossed a bad battery and a possible bad throttle body caused my problem. I have no idea if the throttle body was the issue as even after they replaced it, it threw the voltage code pertaining to the Throttle position sensors, we're gonna give it a few days and see if the new battery fixes it, otherwise we have to chase electrical gremlins as they are not covered under GM's warranty when your bumper to bumper runs out. I will keep you all posted. Fingers crossed!
  • gmcustsvcgmcustsvc Posts: 4,113
    What is the mileage on your Impala, christine68?

    Sarah, GM Customer Service
  • I have a 2006 chevy impala and my service throttle control and reduce engine power lights keep coming on!! I have had a something replaced on the gas pedal already (cant remember what) it was good for a while now its doing it everyday!!! I can pull over and cut the car off and some times it fixes the problem. It is sooooo aggrivating only going 40 mph i am scared I'm gonna cause a wreck!! I have noticed my car heater will not heat up while its in idle.are the two connected? I dont know what to do
  • gmcustsvcgmcustsvc Posts: 4,113
    tracy4511,

    We're sorry to hear that you don't feel safe in your vehicle. Are you at all considering working with a GM dealership to get this looked into? Let us know if we can be of any assistance in that process! We can be reached at socialmedia@gm.com (include your name and contact information, the last 8 digits of your VIN and mileage, and a summary of the situation).

    Sarah, GM Customer Service
  • Man so many replies top this message, my impala has 44,000 miles and is a 2009. Seem to be different fixes for same message. Unless I'm misreading. So a little confused. Replies would be welcomed. This is a scary thing to happen driving anywhere. My dealership is one that went by by. So not much help, was purchased new late Oct of 09.
  • trumble09trumble09 Posts: 13
    edited February 2013
    Depending on the code your car is throwing when it goes into Reduced Engine Power it can be several different fixes... P2138- Accelerator Pedal Position seems to indicate a bad Gas Pedal Sensor(Which isn't covered outside of the 3 year 36k bumper to bumper), P2135 a throttle body problem, more specifically Throttle Position sensors not agreeing on a voltage. So have your codes read at the dealer or an Auto parts store (usually for free) and it will indicate which problem you're having... my 2009 was throwing a throttle body code and the dealer replaced mine for free under the 100k mile Powertrain warranty, after 2009 they removed it from the powertrain warranty. After replacing the throttle body it still persisted, so We've kind of narrowed it down to a bad battery or bad wiring to the throttle body. If you've read previous posts the gas pedal is an easy 70$ self-fix that involves removing some bolts, plugging the new pedal in and putting the bolts back. I would go get a free scan at a parts store before taking it to the dealer, as my diagnostic fee at the dealer runs 100$.
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