so ive had some headers and up pipe fitted to my 03 wrx and this fault code came up p0171 which is lean bank 1 done some research and put it down to the increased air flow so i had the car mapped again wednesday had the light reset car was mapped job done until the next day the light came back on ive checked all the obvious loose pipes broken clips the inlet pipe has was broken so ive changed it but it still on so im thinking it might be the headers they sound like there leaking from inside the car but not when you stand out side if they was leaking would it cause this code?

 

also the tempreture sensor that was in the cat in the up pipe was replaced with a 2.2k resistor

 

anyone have a idea what it can be

 

OBD-II Trouble Code: P0171 System Too Lean (Bank 1)

Just found this if it's of any help to you.

 

was checking headers over again today and noticed theres a crack around the fitting for the lambda sensor so have i just found the cause ? gonna get it welded asap to see if this works ohh i never notied this before because of the heat wrap around it lol

 

well had it welded and code has come back up so I'm sort of baffled now if there was a problem with the maf or the lambda the mapper would of picked this up so i'm stumped anyone got any ideas

 

had 0304 missfire on 4 come on all the time on my bugeye sti went mad nearly trying to sort it out and got it turned off in the map last week by simon at jgm,was told that sometimes the bug throws these codes for no apparent reason ! wot my scoobs do you have ?

 

The Bugeye / Blobeye random CEL generator at it again, The DENSO ECU for the bugeye was a massive improvement over the JECS unit for the classic.........it just took a few years to iron out the faults LOL

I'd have a word with the mapper again

Shaun

 

i have a 03 blobeye the light came on when the headers and up pipe were changed i had to put the 2.2k resistor in the temp sensor because there were no fitting for it but that should be ok ive checked to see if it has blown but its fine sooo?

 

I know this is an old post, but I have just fixed the P0171 CEL code that was popping up on my 04 WRX.
I ran through nearly everything on this list and no avail:http://forums.nasioc.com/forums/showthread.php?t=475620

It turns out the cheap atmospheric BOV the previous owner had installed was leaking (spring was weak and allowed air to leak under normal/high load). Reinstalled the recirc valve and it runs perfectly with no fault code!

IMO - Leave the recirc valve on as the car runs better with it. MAF readings are false when atmospheric BOV's are installed.