Error Code P1131
 

My 98 Expy spit out the code of 1131 on the OBD 2
when I checked because the "Check Engine" light came ON.

I looked up the description and found that it is a

HO2S problem making the engine run Lean. What does this
mean and what do I need to fix this problem.

The guy at Autozone said, it could be triggered by
a loose Gas tank cap also, sometimes.

Any more light on the matter?

Error Code P1131
 

Zenpal,

I am new to this forum. I have the same issue with my 2000 f150. I have a post in the truck section, 1997-2003. (Martinjose) Based on the response I am getting sounds like the O2s sensor is bad. You can visit my post. Hope this gives you some answers. I am going to replace the upstream 02s in my truck.

Let me know what you findout.

Martinjose.

Error Code P1131
 

martinjose,


Thanks for your response. However, my code was 1131 and
yours was 1132. But I guess, mine is still something to do
with the oxygen sensor. Let me know how your f150
behaves after you replace them.. How much do they cost each.

To clear the code, you can have AZ erase code using their
OBD 2 gadget that they used to read the codes. This will
get rid of the "Check Engine" signal.

zenpal.

Error Code P1131
 

zenpal,

Not good results. I replace both upstream O2s and still got the SES light. Replace air filter and same results. Yes, AZ can clear the SES codes but will return back on after a couple of miles. Also disconnect the battery will do it also.

Are you get carbon, black stuff, coming out of your exp mufflers? I am getting the carbon. I hope to get some more info on what I can do next.

Buy the way, O2s cost about 50 bucks at AZ.

Take care.

Error Code P1131
 

martinjose,

The AZ tech told me that the code 1131 is nothing to worry about since it is something very stupid. But the "Check Engine"
light keeps bothering me.

How do you check for carbon in the exhaust.

Hope we can find a soltution to this soon.

Zenpal

Error Code P1131
 

zenpal,

Just floor it in park. If you see black residue on the ground after this, that is carbon. Plus, run your finger through the end of the muffler, if it comes out very black, carbon residue. When I bought the truck, the muffler was clean of carbon. Carbon residue started when the SES light came on.

I took my vehicle to the ford shop for dianostic since the O2s fixed didn't help. They found the PCM had a short causing the fuel injector to push to much gas. Luckly, the PCM is covered under Ford emission system warranty. 8/80, so no charge to fix it. Lucky me.

Hope this helps.

Error Code P1131
 

Before you guys go any further, read the Expy Owners' Guide that our moderator has put together. There is an article that talks about your PCV valve & hose repair. Check it out, this inexpensive fix could solve alot of big headaches. The problem has been known to kick out DTC codes for O2 sensors, so it is worth a try.

Error Code P1131
 

I was feverishly trying to establish whether or not the PCV problem could be related.

It's worth a shot - what bites is that the 1131 code is familiar - I just can't remember where I saw it. I think it was PCV related.

XXL

Error Code P1131
 

Here is a handy ref. manual for obdII codes:

http://www.obdii.com/codes.html

If you have a chance, check out the rest of the site for other good reference material and tshooting.

Error Code P1131
 

Thanks Bigmattxxl and Rtpjunior for your inputs.

I took your advice and read through the PCV valve and
Hose repair on the EOG manual. But I didnt get
the 171 or 174 codes. The idle sounds good and
dont hear any missing. The gas mileage is around
15. I am not sure about the "lack of power" though.

Any help that addresses the OBD code of 1131 is appreciated.

Please advise.

Thanks

Zenpal.
98 Exp 4.6L 4x4 3.55LS

Error Code P1131
 

P1131 means ho2s11 is not switching. The fix is usually to replace it, but just the wiring to play it safe.. The mechanic who said not to worry about it is wrong. With the gas price up I would keep my vechile running at top shape.

Error Code P1131
 

I understand HO2S11 is Oxygen sensor but are you saying I can change the wiring instead of the oxygen sensor. Where can I track the wiring location pertaining to this oxygen sensor. I am not quite at home with the hood open myself but if you can give me some good instructions, i can get some help.

Lead some light fore me please!!


Zenpal.

Error Code P1131
 

I mistake on typing, check the wiring to make sure there are no broken wires or wires are not rubbing through.

Where are the O2 sensor located under the hood or do I have to crawl under the truck, BTW I have a 99 Exp

They are fore and aft the cats.