Engine throwing code: P1131

[AquamanCHS]

Okay.. so...

A few weeks ago my car started running rough and would constantly smell like gas (waiting at stop lights, parking). Also, when idling, the engine would rev from 500 - 1000 rpms for about three revs then settle at 750 or so.

The check engine light came on and I had it scanned, resulting in two codes of "P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1"... I read up on this some and I replaced the MAF.. when I took out the old one the sensor wire things were filthy so I figured I had gotten to the bottom of things.

The car ran fine for a few weeks then suddenly a few days ago I get the check engine light and I smell the gas again. It also started reving againI should also mention that my gas mileage has gone to crap since this started. If this isn't the MAF then what could it be?

 

[triggz]

Sounds like your O2 sensor went bad. Did you reset the ECU when you changed the MAF? That would explain why it ran fine for a while.
But you need to replace the forward-most sensors. You said it gave you TWO codes? Or a duplicate of the same exact code?

 

[340.29m/s]

Yup, sounds like O2 sensors need to be replaced.

 

[AquamanCHS]

Are the sensors hard to replace/get to? Are all sensors the same or do I need different kinds fo left and right? Where exactly are the sensors, anyways? The same ones that are in the midpipe?

 

[96s281]

Are the sensors hard to replace/get to? Are all sensors the same or do I need different kinds fo left and right? Where exactly are the sensors, anyways? The same ones that are in the midpipe?

Same questions here!! I would like to know as well

 

[03gtmustang]

I have the same code, but it came up after I installed my 75mm t/b and plenum. Could it still be an 02 sensor?

 

[DELOS02GT]

I have a code in mine for the bank 2 sensor 1. I was tolod that the O2's that Ford puts in get full of junk and don't read anymore. Bosch is the way to go and that sould take care of the problem. I need to do mine but I'm to lazy and don't feel like getting under the car yet. The O2's are pretty easy to do. The front 2 in mine might be a pain, but the rears are easy. If they have been in the pipe for a while they might give you a hard time, but they will come out. Just remember to put some anti-seize on the threads just in case you need to change them again, or in my case, put the stock H on for emmisions.

EDIT: After I put the mid pipe on I got the code. I thought it was the rear O2's but when I put the Diablo on it said it was the front O2. I talked to guy that knew a Ford tech and he said our cars didn't like it when we put a diff. mid pipe on and the O2 starts to act up. He also said that the Bosch O2's have slits in the side and block the black crap from building up, and the Fords don't. The code on mine says the O2 isn't sending the signal fast enough...so that would explain it.

 

[96s281]

After I put the mid pipe on I got the code. I thought it was the rear O2's but when I put the Diablo on it said it was the front O2. QUOTE]

Hey DELOS02GT, are the front and rear sensors different? I'm heading up to Ford today to pick up a front bank 1 sensor but I want to make sure it's the right part, the guys at the parts shop didn't sound too knowledgeable on the subject.

 

[mustangrmyk]

The fronts and rears are different. Don't mix them up. I got Bosch O2's from NAPA for my '96 GT and when I took them out of the box, they had Ford logos and part numbers on them. The were not hard to swap. Oh, by the way, they were about $25 less than the dealer per sensor.