Check engine light

i have replaced all 02 sensors (after market)and manifold gasket and the light still comes on code reads p174, p1131 what should i do now???

You said the light “still comes on” so I’ll assume the codes were cleared after the work.

P0174: bank 2 lean condition. Did you happen to clean the MAF sensor? And/or check for vacuum leaks? For this, those are the first 2 things I would do. I wouldn’t expect a new O2 sensor to fix it since the O2 sensor very well may be just reporting what it is supposed to.

P1131: O2 sensor short circuit. Did you actually check the whole circuit to the O2 sensor first, or just replace the sensor? This doesn’t mean that the O2 sensor itself is bad - it means that there is a problem somewhere in the circuit - check the whole wiring for the sensor.

yes, codes were cleared, no engine light on for 2 months, then ck engine light comes on, replaced manifold gasket, codes cleared, then 4 months later ck eng. light on again (now). no i didn’t not clean the maf but i did ck for vac.leaks and there were none and no i didn’t check the whole circuit to the o2 sensor

Maybe this article, from, will help:

Maybe now would be a good time to say what kind of car you have.

well i did that in the begining but again, its a E250 ford van and i took your suggestion and cleaned the MAF, much better so far it runs smooth - thank you cigroller

Yea for some reason everyone seems to be using the TAG for their car information.

DTC P1131 is for “Lack of HO2S11 switches. Sensor indicates lean”. This is bank 1.
DTC P0174 is for “System too lean – bank 2”.
So, both banks of the engine were indicating lean. Evidently, the lean condition was caused by the dirty MAF (Mass Air Flow) Sensor sending the wrong information (air flow amount) to the engine computer.

I have come tom guess that the new thing for entering Make & Model just deposits the info in the tag line.

Except apparently on a Subaru where P1131 indicates an O2 sensor circuit short - as near as I can tell. I knew some codes were manufacturer specific, but I never thought the same code could indicate different things across manufacturers.

sparklebrite - glad to hear you got the MAF straight. Let us know if the codes stay off.

DTC codes over P1000 are “enhanced codes”. Their meaning is whatever (within reason) the car maker chooses.
For Ford and Mazda, DTC P1131 is defined as stated previously.
For Jeep, Dodge, Chrysler, DTC 1131 is defined as “Fuel pressure regulator valve”.
An enhanced code is more specific, on a particular code, than the standard code (under P1000). It conveys more detailed information.
I use a little DTC Code Lookup Program I got from I can search (almost) any car DTC code with it.
Here’s another source for DTC Code definitions:

Excellent info - and links! Thanks hellokit.