98 Cobra Check Engine Light - p1131 code

[C. Johnson]

My wife called me yesterday at work and told me her Cobra had a CEL. I told her to stop at Autozone and get them to pull codes. They told her P1131. Now I dug around a bit and found that is a O2 sensor code. I also read that an exhaust leak could cause that. Well, she had a leak just the day before. The guy that put a clutch in the car didnt get the H-pipe tightened up good at the header on the pass side. I fixed the exhaust leak before the CEL light came on.

I disconnected the battery last night to clear the code. I drove it around the block and it never came back on. She drove it today and it did come back on. It is very cold (25 - 35 degrees) too.

The car does have 108k miles on it but it has never given us a problem. No mods other than gears. I know its probably time to replace them!

Does the code P1131 tell which O2 sensor of the four is at fault?

At $50-$75 a piece, I would like to keep the cost down to a minimum and try not to buy all 4.

Suggestions?

Thanks
Casey

[96MC]

It's definitely passenger side sensor. Not sure if front or rear, but I think it is the front one, based on this link:
http://www.corral.net/forums/showthr...ighlight=P1131

[Slithering_Joe]

real quick....
Clear the codes. Switch the sensors from one side to the other. Drive the car until the CEL illuminates. Check for codes. If the code indicates now the other bank then it's the sensor. If the code returns to the same side then you have an fuel injector issue or an exhaust leak on that side of the engine. A faulty MAF will set bank 1 and bank 2 related codes

[C. Johnson]

I think I fixed it.
The car has 108k miles on it and just had a clutch put in it. I made sure the exhaust was good and tight and all the O2 sensors were hooked up and the wires werent frayed/burnt. I then changed the fuel filter on it, cleaned the K&N filter and cleaned the mass air meter element. Fired it up, drove it around a bit and the it hasnt come on again. The wife was pleased because she was tired of driving my truck!
It should hold up for 2-3 months and then she'll be in a Mach 1 (I hope).

Thanks guys
Casey