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Engine Code P1131


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#1
dclub01

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P1131
Air/Fuel Meter Sensor

That's the code i pulled at autozone. The guy there tells me it's the MAF sensor. So i pull it and clean it with some carb cleaner and reset the computer. The check engine light goes out and a week or so later, the light comes back. I clean it again and the whole process starts over...

Any suggestions? Is this the MAF cause i'm about to go and buy a new MAF...

Just wanted some input from you guys before i go. In case you all are wondering, that's the only code that comes up.

Thanks!

#2
jpit

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It could very well be a MAF sensor but code P1131 indicates that your upstream O2 sensor has sensed an 'always lean' or 'slow to switch' or 'lack of switching' condition. It indicates the fuel/air ratio is trying to correct rich for an overly lean condition. Lean condition is set when the O2 sensor stays below .45volts. As you may already know, a good working O2 sensor is constantly switching between rich and lean detection(less than .4 volts to greater than .6 volts is good). You could possibly just have a bad o2 sensor. And of course your maf sensor works hand-in-hand with the O2 sensor and ECU to deliver the correct amount of fuel so you're right in that it could be a MAF sensor problem. If you have the Haynes manual go through the MAF sensor checkout. It may help you out.

Many other things can cause this code. Make sure you don't have any air leaks between your maf sensor and your throttle body such as a cracked/broken resonance chamber or hose or loose clamps. Any un-metered air can cause a p1131 code to set since it is creating a lean condition. Any vacuum leaks can also cause it.

#3
snailman153624

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Try testing your MAF per the instructions in the Hayne's manual, but it wouldn't surprise me if it has gone out.

Also, make sure that you have no air intake leaks.

EDIT: Damn, I'm burnin' CD's and DVD's while I browse the forum. Beat me to it :angry:

#4
dclub01

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I don't have a haynes manual, could anyone tell me how to test the MAF sensor? I'll pay a visit to the local library to see if they have one. Thanks!

#5
jpit

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Probably easier to show you the pics out of the Haynes Manual:

#6
jpit

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Here are the instructions to go with the picture. Backprobe using 2 sewing needles so that you keep the connector still connected at the MAF. Red probe on the MAF and black probe on the MAF RTN lines.
Set your meter for a low scale DC volts setting. Sorry about the pencil marks on the page but that was from when I was checking mine. Good luck. You may still want to think about the O2 sensor also.




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