Which parts fail
Components named in complaints (accelerator pedal, throttle, sudden acceleration, cruise control).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2009 Chevrolet Impala owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2009 Chevrolet Impala. The contact stated that while driving at an undisclosed speed on separate occasions, the messages "Reduce Engine Power" and "Service Traction Control" were displayed on the instrument cluster, and the check engine warning light was illuminated. Additionally, the contact stated that the failure reoccurred while driving on a bumpy road surface and while turning the steering wheel. The vehicle was taken to an independent mechanic, where it was diagnosed that the throttle position sensor had failed and needed to be replaced. The vehicle was repaired; however, the failure recurred. The contact stated that her father used an OBD reader and retrieved codes indicating that the throttle position sensor was faulty and needed to be replaced. The vehicle was repaired; however, the failure persisted. …
The contact owns a 2009 Chevrolet Impala. The contact stated that after starting the vehicle and shifting to reverse, the check engine warning light illuminated. The contact continued to reverse the vehicle and felt a pulling sensation. The "Traction Control" failure light illuminated. The contact decided to move forward and park the vehicle. After several hours, the contact restarted the vehicle and the check engine warning light remained illuminated. The vehicle was then able to be driven. The failure occurred several times after the tires were changed. The contact linked the failure to NHTSA ID Number: 10090054 (Vehicle Speed Control, Engine). The vehicle was taken to the dealer where it was diagnosed that the accelerator pedal failed and needed to be replaced. The vehicle had been repaired. The vehicle was not returned to the dealer when the failure recurred. …
My car has started slowing down abruptly and displaying Engine Power has been Reduced at random times, but has become more frequent. I have had an independent service center tell me it was the throttle body, so they replaced it. That didn't fix it, so they replaced the accelerator pedal/sensor. It still is happening and when on the interstate, it is so dangerous to slow down with no warning because you can get rear ended quite easily. This first started August 2021 when my wife and I started on a vacation and had to turn around and go home and is still happening, only more frequent. This past Saturday 7/16, I was traveling on Interstate 77 and the engine power kept cutting down about every 10 minutes, so I had to pull over and cut the engine off for a while until it reset. I can't trust it to go anywhere.
While driving the car it would pop up a message saying "ENGINE POWER REDUCED". Today while driving it home it popped up with a message saying "STARTING DISABLED, SERVICE THROTTLE" and then the car wouldn't drive and I had to pull over on the side of the road. For months now when I drive and accelerate at times the car would almost grind. I believe it has to do with the traction control or the transmission.
The airbag light comes on intermittently. Was in a collision and the airbag did not deploy. The car was repaired but airbag light still comes on. Also the horn does not work when I press on the steering wheel. The cruise control does not work either. The lights on the cruise control buttons do not light up.
For a few years I've had problems with the accelerator pedal. The first time was roughly two years ago when the car completely locked up and shut down on the highway just before rush hour. I received an error code to check traction control and that the engine power is being reduced. The car then looses speed dropping drastically. The first time I was in the fast lane on the highway and the vehicles computer system shut down. The steering wheel locked making it very difficult to veer off to the side of the high way. Luckily no other vehicles were directly behind me, and I was able to get the car to the side of the highway accident free. I've never been so afraid and terrified in my life. I fear this issue will cause fatalities that can be prevented. I had the car serviced at a Chevrolet dealership in ann arbor mi which was an expensive fix! …
My car was taken into the dealer to check on the "service engine soon" warning and I was informed that the computer showed it as an apps issue. They checked the apps and I was informed that they couldn't find anything wrong and that it had been reset within the computer system and I was good to go. Two months later while traveling at a speed of 55 MPH on a highway, the service engine light came on, service stabilitrak appeared on the instrument panel, traction control off light up on the instrument panel and then the ring tone and the "engine power is reduced" came on the instrument panel. The next thing I knew was that I had absolutely no acceleration at all! I was extremely fortunate that the vehicles behind me were far enough behind me and I was able to get off of the road and on to the shoulder. …
While driving on the highway at approximately 70 MPH the car began to lose acceleration and dropped all the way down to 40 MPH. The check engine light, service traction control, service stabilitrak, and reduced engine power message displayed as well. The car began shaking and would not accelerate. I had to pull off to the side of the highway and turn the car off to try and get the issue to subside. Once back on the road, not more than 3 miles later the issue surfaced again. I ended up having to get off the highway and drive (very slowly) back to my house. Not sure if it will be safe to drive back to the dealership to be addressed. I have replaced the wheel hubs and throttle pedal sensor in the past few years in an attempt to correct. This was an intermittent issue until recently and even after having it fixed by a certified Chevrolet dealership, the issue occurred again. …
I was on the interstate, going the speed limit. I had the cruise control on when the car alerted me that the engine power reduced and service traction control. I continued to drive as these messages have appeared on my car before. I traveled another 40 miles along the interstate and was about a mile from my exit. I was passing an over-sized tractor trailer going up hill when the car displayed starting disabled throttle service and the car shut off. I was in the left lane and had to initiate my emergency lights and wait for the tractor trailer to pass me so I could move the car over to the right shoulder. As the car was completely shutoff and was just coasting, I had to fight the steering wheel to control the car. …
I was driving on the highway and all of the sudden check engine light and traction control light come on. Warnings service traction control and reduced engine power are displayed and all but shuts my car off in the middle of the highway causing cars to slam on their brakes and swerve barely missing me. I get over to the side of the road and turn the car off. Then turn the car back on same messages and won't go no where. Do the same thing again only waiting longer and no messages but check engine light still on. I drive home. Next day no warnings or lights. Couple weeks go by does the whole warnings and lights and slows car down again but doesn't completely shut it down. I was in regular street traffic this time about 35mph. And now it's more frequent sometimes a couple times a day to once every day or two. This needs to be looked at. …
Acceleration complaints in other Impala years
Frequently asked questions
How common are acceleration problems on the 2009 Chevrolet Impala?
NHTSA has 130 complaints about the speed control & acceleration of the 2009 Chevrolet Impala, 16% of the model year's 824 complaints. The component named most often is accelerator pedal (8 mentions).
Is there a recall for 2009 Chevrolet Impala acceleration problems?
No. NHTSA lists no speed control & acceleration recall for the 2009 Chevrolet Impala, though it has 5 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2009 Chevrolet Impala acceleration problems start?
Half of the complaints with a recorded mileage happened before about 91,000 miles, and 6% before 25,000 miles.
Is it dangerous?
Owners linked 2 crashes, 0 fires and 0 injuries to speed control & acceleration problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.