Codes P0171 and P0174

Not the pressure regulator?

Okay Roy Thank you very much. I don't know how to decipher those numbers. I would have been off in a different direction, but you noticed the fuel pressure low. The car has about 115,000 miles on it and from what I have been reading, that's about when fuel pumps go out on those models. So thanks again I appreciate it, looks like I got a lot of work ahead of me.

Hello, I hope I am communicating with Roy. It's been a few weeks, but that is who I was working with. Anyway, I put a fuel pump in. As it turned out, the 2006 Jaguar XJ8 is one of the easiest fuel pumps to replace. The car runs great. Before, when I tromp on the accelerator the car would bog down, the check engine light would come on and it would smoke like hell and the Restricted performance message would come on. Now when I tromp on the accelerator, it takes off smooth and runs like it is supposed to. However the codes came back, P0171 and P0174. I am attaching a print out of live data. I know it shows fuel pump pressure at 47 but it can't be fuel pump the car runs great.

Thank you. I got a new MAS air flow sensor, don't have a PCV, I better check for leaks. I'll let you know.

I replied to this but I don't think it went through so I'll do it again. Looks like you did it again Roy. I had a little rip in the rubber boot that holds the MAF sensor to the throttle body. I repaired it, let it sit overnight and drove the car all over town today and didn't get any codes. It didn't take much, that was a small rip. Looks like I got away cheap. Thanks again Roy you know your stuff.