The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 01 check engine light...Need help with code P0171/P0174

**hatzie** · 10-24-2022, 07:14 PM

P0171 is Bank1 lean
P0174 is Bank2 lean

You're going to spend a ton of unnecessary cash loading the parts cannon and blasting parts at it.
Since it's both banks I'd start by checking your fuel pressure at the test port on the engine.

It could be O2 sensors but both banks failing at the same time is not a normal failure mode.

10-24-2022, 07:14 PM	#3
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,975	Re: 01 check engine light...Need help with code P0171/P0174 P0171 is Bank1 lean P0174 is Bank2 lean You're going to spend a ton of unnecessary cash loading the parts cannon and blasting parts at it. Since it's both banks I'd start by checking your fuel pressure at the test port on the engine. It could be O2 sensors but both banks failing at the same time is not a normal failure mode. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful. Last edited by hatzie; 10-24-2022 at 07:20 PM.