Codes P0171 & P0174

**tamu130** · 08-29-2005, 03:46 PM

what could be causing these codes? they have been on for a bit. i can clear them and they will stay of for a while but come back on. and occasionally it will go off itself but not for long.

thanks in advance.

Spartan_Angel · 08-30-2005, 12:45 PM

Just wanted to say Gig 'Em ... but I can't help you with your problem, lol

**2001NBMZ28** · 08-30-2005, 02:40 PM

You're running lean on both banks - sometimes people get these codes with an aftermarked MAF - assuming your stock here's a few things to check out on the diagnostic page in Helms when you throw both codes together:

exhaust leaks
precat 02 sensors secure
vacuum leak
intake air leak

I'd also make sure the MAF connection is good and the MAF itself is clean.

**ninobrn99** · 09-08-2005, 06:57 AM

have you recently messed with the intake manifold? if so, then thats your problem. are you running a k&n filter? you maf elements could be covered with oil from it and be throwing it off also. If its been that way for a while, you may also want to consider new o2 sensors. What mods do you have done and whats the last thing you messed with?

**ReSSurected** · 09-09-2008, 01:19 PM

I have the same exact thing going on with my 00 z28. Except when they come on my idle starts to drop. I was thinking it was the 02's. I did not know it could be this other stuff.

**Rob Mellinger** · 09-10-2008, 07:23 PM

I had same code problems, turned out to be slp maf. Installed stock one, no more codes. 200$ waste of money.

**0rion** · 09-11-2008, 08:01 PM

yes, a list of mods would be helpful.

**mrr23** · 09-14-2008, 10:41 AM

if stock MAF, then a vauum leak is most likely. one of two spots. the most likely is the rubber line between the PCV valve and intake. it likes to rot from the underside. typical. second would be the EGR tube seal slipped out of place.

**ReSSurected** · 09-15-2008, 02:39 PM

Originally Posted by mrr23

if stock MAF, then a vauum leak is most likely. one of two spots. the most likely is the rubber line between the PCV valve and intake. it likes to rot from the underside. typical. second would be the EGR tube seal slipped out of place.

This was exactley my problem! 5/16 fuel line for a 1.50 and now it runs great!