I have a 2005 Toyota Tacoma PreRunner 4.0L. Mil light on, Faults p0171(system too lean/bank 1) and sometimes p0174(sytem too lean bank 2). From online information, I have checked for vac leaks best possible (none found), replaced mass air sensor, replaced pcv valve. Fault reocurrs after clearing faults. Most info points to dirty or bad mass air sensor but I have cleaned original sensor and replaced sensor with a new Denso brand sensor and no changes. I’m thinking it may be fuel pump related, but unfortunately don’t find a test port easy to get to to ck fuel pressure. Does part of the intake have to be removed to get to the fuel rail test port? I was a VW tech for 35 years and on most VW models I knew what problems were most likely to cause certain faults. My question is are there any Toyota techs out there that can tell me what they normally see with these faults. How often do you see fuel pumps going out on these Tacomas? Do you see these faults when they do? Any ideas will be appreciated. I will try to attach several scan data printouts.
Faults P0171 and P0174
- Thread starter Rodney J
- Start date
sfstud2002
Well-Known Member
I can check for any TSB'S when I get back to work on Monday.