P1131 code on 1999 FORD Explorer XLT SOHC

bbrizendine · February 16, 2009

Have cleaned (4 times) MAF and replaced it. Engine still rough with engine light on and P1131 code. Points to 02 sensor. How do I tell which one? Where is it? I found one on left side. Can't find one on right side. I was told that there are 2 above the cat converter and 2 below - right and left side. I think the ones below the cat converter are a different code. If that's true, then how do I tell if it's the right of left one? Note - I'm a decent backyard mechanic, but don't know to use a voltmeter or do auto electric testing. How hard is it to replace?

Sams01XplrSprt · February 16, 2009

welcome

CDW6212R · February 16, 2009

I replaced my RF O2 sensor about two weeks ago, same code and engine. To get at it, pull the right plastic inner fender out from the back. You can most easily get to it from the side along that back edge of the wheel well. Both of your front O2 sensors are the same part number. I suggest buying the Ford part, it will plug right in. The other brands require building the wiring connection ends, the wires come separate from the connectors.

gijoecam · February 17, 2009

H40 DTCs P1131, P1132, P1151 AND P1152: UPSTREAM HO2S NOT SWITCHING. DTCs P1130 and P1150: FUEL SYSTEM NOT SWITCHING AT FUEL TRIM (RICH OR LEAN)
Note: It is necessary to address all Continuous Memory Ignition and Misfire DTCs, if received during Continuous Memory testing, before addressing any KOER HO2S DTCs.

DTC/HO2S Reference List

HO2S-11 = DTCs P1131, P1132 and P1130
HO2S-21 = DTCs P1151, P1152 and P1150
Check intake air system for leaks, obstructions and damage.
Check air cleaner element, air cleaner housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks.
Are any of the above concerns present?

So, what makes you think that the sensor itself is bad? Could it not be just a simple vacuum leak in a PCV hose? A $10 hose sounds like a better deal than a $90 O2 sensor that may not fix the problem...

The code does not indicate that the sensor itself is bad. The code simply indicates a lean condition being detected by that sensor. It could, in fact, be correct. (I know, it's a novel idea) Until you've done a complete diagnostic, there's no sense in throwing parts at it...

-Joe

wyochimneysweep · February 17, 2009

most of the time if its a vaccum leak both sensors willshow lean

gijoecam · February 17, 2009

wyochimneysweep said:
most of the time if its a vaccum leak both sensors willshow lean

Depends on where the vacuum leak occurs... With the split intake on the SOHC motor, and two vacuum lines attached to it, it's possible for the vacuum leak to only affect one bank...

edit: Or, if it's the lower intake manifold gaskets, it can depend on which side(s) is(are) leaking... Vacuum leaks don't necessarily affect ALL cylinders equally...

CDW6212R · February 17, 2009

The code definition that I read pointed at the one sensor, and the wiring for it. I don't know how many different definition sources there are. I knew I had no more obvious problems, and the wiring, connections were good. Do check those, as well as the obvious vacuum leak sources, tune up items etc. I decided based on mileage and the definition that it was a good time for me to swap the RF sensor. I had it for my 302, it's the same sensor.

desertbum8 · June 7, 2009

Hey guys. I have had the P1131 and P1152 codes show up on my truck. The truck runs great after it has warmed up, but it still has a rough idle. When the engine is cold it has a really rough idle and the acceleration hesitates and sounds like the engine is misfiring. I just replaced the DPFE sensor and it helped a little. I was thinking my bad Cats messed up an O2 sensor. Does anyone have any ideas on how to check my sensors to see if they are bad? Thanks!

P1131 code on 1999 FORD Explorer XLT SOHC

bbrizendine

New Member

Sams01XplrSprt

Southern Cali Explorer

CDW6212R

Hauls the mail.

gijoecam

Village Idiot

wyochimneysweep

Well-Known Member

gijoecam

Village Idiot

CDW6212R

Hauls the mail.

desertbum8

Active Member

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