• Tiny
  • jgubash1985
  • 1997 Ford Explorer
  • 6 CYL
  • FWD
  • automatic
  • 165,000 miles

I have a 97 ford explorer and it threw the code p1131. It idles really rough at times and sometimes even kills. I can also smells unburned fuel coming out of the exhaust sometimes too. I was just wondering if you had any ideas on what it could be

Do you
have the same problem?
Wednesday, January 19th, 2011 AT 6:01 PM

1 Reply

  • Tiny
  • bluelightnin6
  • Expert
  • 17,061 posts

P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1

Any of these could be the cause of the code.


* Short to VPWR in the harness or HO2S
* Water in the 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)
Start by checking all the parts you can visually check. More than likely it is an exhaust leak before or near the HO2S(s)

Was this
Wednesday, February 9th, 2011 AT 2:53 PM

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