I was wondering if anyone knows what that code means? (P 1131). The check engine light on a friend's F-250 kept flashing repeatly lately. He went to a part store to have the codes read, and got the following: 131 for the oxygen sensors( he replaced the oxygen sensors--it was cleared for awhile), PO 304 for this miss firing on the fourth cylinder and this one says refer the manufacture code P 1131. But he doesn't have the slighest clue on that one..

Thank you in advance, for any help.

-Melaney

P1131 Lack Of HO2S11 Switch - Sensor Indicates Lean

this is coming from the right, front sensor.

Thanks Brian...What causes that?- do you know?

-Melaney

that DT code specifically points out the right front sensor, however if he has replaced them all already this code is also one that is tripped when you have a bad MAF sensor. (Mass Air Flow).This will be located on the intake somewhere near the air filter. wish I could be more help, the PSD's are a bit out of my knowledge range.

Hopefully its just a connection or the codes need to be cleared.

I'll let him know about those specifics, and maybe he can re-check it. Appreciate your help/info--thanks!

-Melaney

P1131 Lack Of HO2S11 Switch - Sensor Indicates Lean

this is coming from the right, front sensor.

What briano said. Also Melaney,
The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.
Electrical:
-Short to VPWR in harness or HO2S
-Water in harness connector
-Open/Shorted HO2S circuit
-Corrosion or poor mating terminals and wiring
-Damaged HO2S
-Damaged PCM
Fuel System:
-Excessive fuel pressure
-Leaking/contaminated fuel injectors
-Leaking fuel pressure regulator
-Low fuel pressure or running out of fuel
-Vapor recovery system
Induction System:
-Air leaks after the MAF
-Vacuum Leaks
-PCV system
Improperly seated engine oil dipstick
EGR System:
-Leaking gasket
-Stuck EGR valve
-Leaking diaphragm or EVR
-Base Engine:
-Oil overfill
-Cam timing
-Cylinder compression
-Exhaust leaks before or near the HO2S(s)
-A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S. aid.

If theres anything Im not clear on, please let me know. I can explain it further to ya, if you like.

Scott

That's a lot of info!! I'm going to write them all down, when I get home today. Thanks for the help and all the info.

-Melaney

N/P Melaney. I can email you that information plus some, if you would like. Instead of having to write it. Email would be faster ;)

Scott