HardcoreFx4

my grandpas 2002 f150 with the 5.4l 2wd with 90k on it, has 6 codes, p0171 system bank 1, p0174 system bank 2, p0136 oxygen sensor, p0156 heated 02 sensor, p1131 system too lean 1, p1151 system too lean 2. reason i posted this was because i dont wanna guess on this, guessing gets expensive!!! has anyone had these same codes pop all up at once?

FallGuy44

I've only had the p0171 and the p0174 come up at the same time. I cleaned my MAF sensor and that fixed it. As far as the others, I will let someone else chime in.

HardcoreFx4

Anyone?

C Michael

Clean MAF and IAC. Disconnect negative battery terminal, reconnect terminal, start and run. Check again for codes. Simple and inexpensive.

redseal97

how does it run? any pinging on accel, hows the exhaust, are the manifolds bad, is the o2 sensor post or pre cat, any recent work under the hood? even an air filter change? tune up done? and fuel pressure? i know that alot of questions but you may have a couple codes unrelated, like the o2 heater circuit, it'll throw a code but after its driven that o2 will come up to temp and operate properly, so how it runs, and if any work has been recently completed are important, also if the manifolds get bad enough they will suck in unmetered air and make the o2's read lean. if no work has been done, manifolds are good, no misfireing or terrible driveability issues, i'ld clean MAF, get a fuel pressure reading and check for vaccum leaks at duct work throttle body, egr and intake, then clear codes, drive until cel comes back on and see what was the first codes that tripped the light. if any recent work was done under hood i'ld start by double checking to make sure hoses where re-installed and clamps tightened. you need to cover the basics before you jump in with both feet. just my nickles worth,( we don't have pennies in Canada anymore)