JimK

2010 Impala LT
While we were driving on I-75 in southern KY, the car suddenly lurched a little and "traction control" and "stabilizer" errors displayed followed by "reducing power." And, the check engine light came on. I called the Chevy dealer and asked if it was safe to continue driving - they said Yes, as long as the check engine light wasn't flashing. We went about 5-10 more miles and it displayed something about "throttle problem" and then "shutting down engine", which it did while we were doing about 70 in the middle lane of I-75. I had to try to steer to the shoulder with no power steering or brakes. Once there, I tried to restart the car and nothing happened - it displayed "starter disabled." We called our road service and they took our info, found a nearby (30 mi.) Chevy dealer who said they would work on it asap if we got it in there. While they were working on setting up a tow I tried starting it again and it started but the check engine was still on. I tried driving a little along the shoulder and it seemed OK so I said hold the tow and we'd try driving it to the dealer rather than wait for a tow truck. I kept it down to 60 and we made it in. They found the problem was the gas pedal position sensor. Fortunately, they had one in parts and installed it for a grand total of $205.
When I asked about the other strange errors they said that when that sensor fails the computer gets totally confused because it senses the car moving at one speed but the gas pedal at a position for a different speed.
The scary part was the complete and sudden shut down of the engine. We were fortunate because there was an opening in the right lane and I could coast to the shoulder. The day before were passing through Atlanta with it's 6 lanes of heavy traffic. A shut down there would have been a disaster.
There was no warning that would have allowed me to get off the road before shutting down.
I will be contacting NHTSA and GM about this potential life-threatening problem.

sledge.impy

If you read these forums and other forums on these recent cars, sudden shutdown/disabling of the engine in reduced power mode appears to happen to enough, especially at highway speed.

It should be in your owner's manual as happening.

JimK

I can understand the reduced power but it should leave me with enough to, at least, pull off thru lines of traffic onto a shoulder. It also gave no warning of the shutdown. As a retired programmer/analyst/asst. prof I feel that I know enough about computers to say this is poor design. Unless the engine is heading for catastrophic failure as indicated by sensors on the engine, it should be up to the operator to determine whether or not to shut down. The driver info could include bells, blinking, warning messages,etc. warning of pending shutdown in X minutes. Mine gave NO warning - the shutdown message appeared just as I felt the engine die.
The only error indications I got were for traction and stabilizer and they went away when I turned off the traction control. And, a traction problem should not be cause for immediate shutdown even if there really was a problem. So, basically, I was driving with a solid, not flashing, check engine light which my dealer assured me I could drive home on as long as it wasn't flashing.
That shutdown while in the middle of an interstate left me with no engine power, no power brakes or steering and put us in serious danger.
If, as you say, it happens enough at highway speed then we, as Chevy owners, should be screaming to the NHTSA.

sledge.impy

Yeah - I agree about these car's computers just shutting the vehicle down on the highway as being dangerous.

Here's one such complaint: (1st post)

https://chevroletforum.com/forum/equ...e-light-62780/

in2pro

GM can design it to completely shut down and stop you dead in your tracks in the middle of the road if that is what you feel would be safer... the function is to allow you to get off the road under the vehicles power... its no worse then having an unexpected blow out or running out of fuel...
Is it startling ? Yes
Is it better to have some ability to drive than none? Yes

You may be able to pull off the road, shut the vehicle down for a few minutes and it may reset and allow you to drive " normally" for a period of time until the error(s) are detected again...
Do get it in for repair as soon as possible...
Believe it or not is actually a good feature to have (limp mode) What's not okay is if it happens a lot with many vehicles...

JimK

I think you missed my point - it DID stop us dead in our tracks. The only way I got off the road was to coast thru a small opening in the right lane of traffic to the right berm. It did not go into a "limp" mode. That is the point of my complaint. It did a complete, engine off shut down. I had no power steering or brakes as I tried to coast off thru traffic on a 70 mph interstate!

thedash09

Had the same problem today! I can only hope that its a $200 fix, I have been unfortunate with cars for some reason.

JimK

Here's the breakdown for my repairs:
$105 for part - "APP sensor" Accelerator Pedal Position
$85 for labor - scan, test, replace part, clear codes, re-test
$8.50 supplies
$6.85 sales tax

JimK

One more follow-up -
I filed a complaint with the NHTSA. While on their website I looked at other complaints about the same/similar problem. It was a long list. There also appear to be about 4 service bulletins that might address the problem. That tells me GM is aware of the problem and has neglected to do anything pro-active about it. Apparently they're waiting for someone to be injured or killed before considering a recall.
Based on that, I also wrote to GM Customer Assistance and sent a copy to CEO Mary Barra basically asking that they do a recall to:
1. Replace the faulty sensor
2. Re-flash the computer to eliminate the full power-off, no warning shut down.
If I hear anything I'll post it here.

thedash09

I got a scan today by autozone. Pulled up a p2122 code. The rep told me I need to replace the whole throttle. Quoted me about 250 for a remanufacture and 130 for a generic. If I commit to this fix I hope that is the only thing wrong and the problem will go away.