Page updated on 04-23-2018

1998 code P1131

09-29-2004, 10:18 AM
Have a 98 Ford Contour getting code P1131. Guys at Autozone told me Saturday was most likely O2 sensor. Bought and replaced it, vehicle ran fine until Monday afternoon, got Check Engine light again, went in and had them reset computer. Seemed fine and got light again yesterday. Now being told that the O2 wasn't the problem and guy I talked to last night couldn't understand why I was told that in the 1st place. He's now telling me to try replacing the fuel filter and the plugs. He also said it could be the air intake valve (something that I don't think I could change) I have the fuel filter, going to put that on Friday, but holding out on the plugs for right now.

Symptoms: 78,000 miles. Car sometimes idles rough at stops and in park, but not always. Once I hit 55-60 MPH can tell there's obviously a problem, like car not getting enough fuel. Having the AC on makes problems worse. Exhaust also smells different after running the car. Have had the car die several times, usually when slowing down to turn or stop.

Help me out guys, I don't have the money to go to a mechanic, especially after spending $70 on an O2 sensor I didn't need.

09-29-2004, 03:52 PM
P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1 (Rear of engine).

I hope you replaced the right sensor. If its the V6, its the top 02 sensor on the rear of the engine.

09-30-2004, 08:23 AM
It's only a 4, so I'm cool. But why am I still having trouble???? It's not wanting to die when I'm idling or anything, but when I hit about 55 MPH, the engine starts running really rough. Also, exhaust smells different than usual. As I said, I've got a new fuel filter I plan on putting on tomorrow. What about this air intake valve? Could that be the problem? He showed me where it was and I'd have no idea how to get to it, with it being under the manifold and all.

09-30-2004, 12:48 PM
I would guess its a vacuum leak somewhere, causing it to run lean then. Check the iac valve.

09-30-2004, 04:03 PM
Funny you mentioned that...they guy at Autozone, which by the way I was pretty impressed with him, thought that too but when he went out and checked it on my car, he didn't hear or sense one. By the way, whats the iac valve?

Thanks for all the help.

10-02-2004, 09:14 AM
Idle Air Control Valve

05-07-2010, 06:38 PM
Can anybody tell me if these fixes worked? I'm having the same code come up. What's the first thing I should fix? Is there a way to test the fuel pressure on this engine?

Add your comment to this topic!