hey guys, I'm new to the community, just got my first C6 and I'm loving it. But I've had the P0171 code pop up twice now. The car only had 17k when I bought it and now it might have 20k on it, and it's a 2008. The first time I thought it might have been because the previous owner pulled the npp exhaust fuse so it would be louder. I put it back in and the code popped up again today. Maybe 2000 miles since the last one. So the issue doesn't seem severe, but I'm not sure. Any one have any idea? I looked for loose hoses, couldn't find any and I can't imagine any filters are bad at 20k miles... thank you guys for the input!

 

Your fuel trims are out of whack.Coulld be 02 sensor issue or even dirty air filter

 

Congrats and welcome to the Forum and to your new C6 !!...normally a dirty air filter will cause a RICH condition so the PCM will subtract fuel if you know how fuel trim works. A P0171 is a left bank lean code BUT you must look at both fuel trims (long term) to help in a diagnosis. When that left bank hits around 23% added fuel the MIL (check engine light) will illuminate. Now if the left bank is only 22% the other bank lean code will not set but now it really helps to look at your O2 sensors and fuel trims with a scan tool. If it was just the left bank lean (bank specific) you can look for an exhaust leak upstream of the front O2 sensor or maybe even a leaky fuel injector O ring...now if that right bank were elevated say at 22% (now we are looking at something that affects BOTH banks/engine) I'd be looking at an air intake leak downstream of the MAF sensor or it can be an "under reporting" MAF sensor (a dirty one)...any driveability issues ??...lack of power etc...??...you can even have a leak somewhere in the PCV system... you really need to use a scan tool to see which direction you'll be going with this !!

 

NPP fuse in or out won't cause this code.

This code is typically because of some sort of leak in the intake track. You need to check all intake, PCV, and vacuum hose connections. It can be a bit of a bitch to find as all it takes sometimes is a tiny slit or crack in a hose that you can't even see.

Ways to find the leak would be to have some way to monitor the fuel trims in real time, and while the engine is running, spraying starter fluid at various places on the engine where it can leak. Got to be careful however not to cause a fire.

The other way is to have a mechanic do a smoke test to find the leak.

 

This is an issue I have been dealing with off and on for a few years. Tried many of the remedies (visual inspection, new air cleaner, new MAF and then scrubbed the new one clean after new codes appeared)and then there it was again. Very frustrating. Then I read this resurrected post. I followed all of the procedures, and for now all seems perfect. In fact, the car runs better and idling is more even!????? I didn't buy new clips. The clips appeared to be too long, so I went to Lowes and bought a few rubber washers and used them with the old clips. That closed the gap pretty much, and then I used some good HVAC type tape. We'll see, but I am pretty optimistic. Worth a try (see especially post #3). Good luck! And welcome to the community. It's a great place to learn from some very knowledgeable people. I know I have and strive to be one of the "knowledgeable" ones at some point.

https://www.corvetteforum.com/forums...-04-040-a.html

**I just reread your post more carefully. Seems those repairs may have already been done. May still be worth checking before you go to all of the other possible issues. The tip-off for me was after I would "get on it" pretty hard or after sustained driving on the Interstate, the code would (and MIL) would appear. Local driving at low speeds did not seem to trigger the codes (MIL). Let us know what you find. I might still be fighting this too..

 

If the MIL appears after "getting on it" like I said looking at fuel trims while driving would nail down your concern !!...may be fuel delivery issue or MAF...with a scan tool the MAF grams/second reading should be "roughly" equal to the engine displacement in liters...my 5.7 liter reads around 6.0-6.3 grams/second at idle...if you only reading 5.0 the MAF is under reporting airflow !!...if you want to gain knowledge look no further than here !!...subscribe to his premium channel for $11.00/month....can't beat it and you will learn and be one of those "knowledgeable" members !!

https://www.youtube.com/channel/UCrf...oy4alB2WXJCIqA

 

Thanks C5---I just picked up a new code reader and appreciate this info. I'll take a look!

 

Which one did you purchase ??

 

The Ancel AD 530