kerwinq

Just took my truck to the shop for P0171 and P0174 codes. They replaced the fuel pressure regulator, and said all was good when I picked it up. The CEL came back on the same day within about 30 miles. Took it back in for the same codes and they do not know what the problem is. They said the fuel pressure was good from the pump so I am not sure that is the problem. They looked over all the vacuum lines and all looked ok. Just had a tune up and replaced the front 2 O2 sensors within the last 6 months.
The CEL came on again a few days later with the same codes. Took it to the shop again, they checked everything again but didn't find any issues. They suggested that I take it to the dealer to have a Computer Reflash done. So the question is what does this do for me? They claim it will reset everything but I want to know that I am not just throwing money at something that I don't need to.
The dealer charges 85.00 to do a Computer Reflash and said it takes about an hour to hour and a half to do. But not knowing what doing this does for me, I want to make sure I am not paying for something that I really don't need. Would pulling the battery cable off for a bit cause the computer to reset itself better than clearing the codes with a code reader?

Is this a good thing to do and is the dealer the only one that can do it correctly?

Thanks, Kerwin

NGM

Good info very complete. OK they have thrown parts at it for you. Now lets get it fixed. Is there a dyno anywhere near you that you can do some pulls on? If so pay for a couple of pulls and if you have dual exhaust I want tail pipe readings from both pipes. If its single then just from the one. If you dont have a dyno near you NBD. Take a can of carb cleaner, while the truck is running spray down the intake and around the throttle body. If the engine picks up there is a vacuum leak. Fix the vacuum leak. Lets start there.

mhiggs351w

^x2. you also might want to check the plug wires. one of the wire heads may be burnt which is common on higher mile motor wire plugs. If it is burnt then thats why the code is thrown cause that wire is not making a good spark. then the computer tells it to throw less fuel making it too lean. Pretty comon. Ive seen it happen and had it happen to mine.

Ty

well, ngm, it looks like you finally got your info.

good luck fixing your problem.

sysman_rick

Good explanation...... to many "Mechanics" throw parts at a problem.
No one will rebate you the costs when the problem is not resolved.

kerwinq

I'm thinking about just taking it to the dealer and having them do a diagnostic. Should have done that first since it is only 10 dollars more for them.

NGM

Thats totally up to you. IMO if you can fix it for little to nothing by doing a few basic checks why not do that? For example, my wifes truck set a code I have never seen before. p1121 Corolation between the MAF and TPS. I was like WTF. I followed the diag tree and found the problem and fixed it for free.

Magas

did you figure it out >
i'm just going through all the posts and replies for P0171 error . let us know.
Thanks

kerwinq

My issue was the MAF Sensor, it was showing that it was running in high elevation all the time. Once that was replaced all was good. Haven't had the code come on for over a year