Sunday morning, my wife & I were returning from grocery shopping, came to a stop, and it stalled. Started right back up, but she said it stalled 3 times taking our youngest to school today. I rode with her to pick him up, and it did it again a couple times. Basically, coasting to a stop at a light or a turn, right as we stop, it dies. Had the codes read, and still, the only one was P0400, the exhaust timing sensor. I figured maybe I'd better change it, and did. Drove to the gas station, and it was ok, but after I filled up, it cut out twice in the parking lot. The ride home, it seemed ok, and maybe a couple times, the rpm'* started to drop, but it corrected itself each time. The only other thing we've noticed, is when sitting at a light, in gear, the rpm'* are steady, about 1200. But there were a couple "bumps" from the transmission? As if you let up on the brake, and then stepped on it again. Thoughts?

I've never heard of an "exhaust timing sensor" . . . ?

P0400 is EGR flow malfunction detected. Could be caused by a bad EGR valve, or bad sensor, or other things.

What part did you change?

Do you have a picture of the old part that you can share?

How many miles on the car?

How many miles have you owned it?

Did you replace the EGR valve yourself?

It'* a sensor for the variable valve timing, there are two on top of the engine, between the valve covers, one intake, one exhaust. Autozone'* system said it was the cause for the code. (It'* been wrong before, especially with the bad coil packs on the '98 Bonneville!) They're round, about 6" long, with a tab for the bolt that holds it on. The intake is on the front, ;and the top of that sensor is gray. The exhaust senor is right behind it, and has a black top, there the plug goes on. The new part was also black. We bought the car in late July, currently 118K, so I believe we've put about 3K on it. I posted previously about the tire pressure sensor, and wondering if it needed a timing chain replacement soon. I also considered there could be some gunk on an injector, or in the fuel system. So, I picked up a bottle of Seafoam cleaner, safe to pour in the tank, which I did. My wife said it was running rough when she started it this morning, but it smoothed out, and didn't stall. But, when she went to pick up my son at 4:30, it stalled several times on the way there, and 9 times on the way back! And the weather'* been near perfect, 60'* this morning, and 70s this afternoon, unusual for NC this time of year! Probably have my wife take it to Mr.Tire tomorrow, for diagnostics. I'll check back in here tomorrow afternoon. Thanks again!

I'm not sure it even has one, these "late model" vehicles!

Your code is for Exhaust Gas Recirculation and you replaced the VVT solenoids?
Looked it up and no EGR and no P0400 for that vehicle. I need to know what codes we are dealing with. use a different scan tool to get codes.

Ah, so a cam sensor or maybe a cam phaser?

Can you post a picture or part number?

My wife took it it in, and they said either the new sensor I installed is bad, or, more likely, the VVT/cam system needs to be recalibrated. So we had to take it to the nearest dealership, Dale Earnhardt Chevrolet. They said maybe they can look at it on Friday. Sigh.

Best of luck!

Please let us know how it goes!

Well. My wife called them to see if they'd done anything. They said it'* leaking oil. Duh, we already new that! Then, they said it'* burning oil, and would she like them to replace the pistons & rings! Well, what about why we brought it in? "Oh. it also needs a timing chain.", and they were "working on it now." WTF? I'm going over there tomorrow morning w/her to get our car back! She never authorized them to do any repairs, just diagnose! I had my company truck (06 Chevy 2500 HD) there once, and that went ok. But this is shysetery as hell! Going to call around, I know there'* another Chevy dealer in Hickory...