codes

Reply Subscribe

Thread Tools

Search this Thread

Jan 12, 2013 | 02:49 PM

Prof2113

Thread Starter

Senior User

Joined: Jan 2011

Posts: 102

Likes: 0

codes

Hey guys. Go the dreaded check engine light today. ran the scanner and got the codes below. Any thoughts would be greatly appreciated.

Thanks!

P1151 Lack of HO2S21 switches- Sensor indicates lean

P1131 Lack of HO2S11 switches- Sensor indicates lean

Jan 12, 2013 | 03:06 PM

timbersteel

Logistics Pro

Joined: Mar 2005

Posts: 4,698

Likes: 47

From: Mexico, Missouri

If the engine is showing both banks lean, could be clogged fuel filter, bad FPR, wiring fault, or simply both O2 sensors are due for replacement. When were they replaced, # of miles since replacement? I have also seen this with contaminated fuel / E85.

Edit: A bad fuel pump has also known to cause this as it cannot keep fuel pressure steady.

Jan 12, 2013 | 05:46 PM

Prof2113

Thread Starter

Senior User

Joined: Jan 2011

Posts: 102

Likes: 0

O2 sensors (3) were replaced less than 5000 miles back(Bosch). Fuel filter less than 10000 . 330,000 miles on the truck.

Guess I will check fuel pressure next.

Thanks for the information!

Jan 12, 2013 | 05:48 PM

Prof2113

Thread Starter

Senior User

Joined: Jan 2011

Posts: 102

Likes: 0

Btw, it's a '96 OBD2 with the 4.9 with all emissions still intact.

Jan 12, 2013 | 06:04 PM

timbersteel

Logistics Pro

Joined: Mar 2005

Posts: 4,698

Likes: 47

From: Mexico, Missouri

I didn't note that a vacuum hose leak could also trip a Lean condition as well as an intake or throttle body leak. Also vacuum canister leak.

Jan 12, 2013 | 06:10 PM

Prof2113

Thread Starter

Senior User

Joined: Jan 2011

Posts: 102

Likes: 0

Thanks! I'll check for a vacuum leak as well.

Jan 13, 2013 | 04:40 PM

Prof2113

Thread Starter

Senior User

Joined: Jan 2011

Posts: 102

Likes: 0

Would a bad temp sensor contribute? My temp gauge is staying way down even when driving on the highway, so I know I need a new one. Maybe I'll replace it while I am checking fuel pressure.