CEL P0031, manifold O2 sensor?

E

Evil Jeff

New member
Yeah, fairly certain my MAF is toast. I'd like to do some troubleshooting before I drop 2 bills though, just to make absolutely sure that's what it is. Anyone have anything lying around from a recent intake upgrade? Gabe?

I'm pushing Runnah to buy the WRX RallyXI has for sale, so I can borrow his.

NOTE: Original title was "Want to BORROW (or buy cheap): WRX 2.0l MAF". Moved here and changed the thread title, as it would appear to not be the MAF now.

 
Yar. It's been working for about a year now, keeping the CEL at bay. Done it 3 times in the past week though, and no results.

Think I might get rid of the K&N tonite for a real filter and clean it again, see if that helps.

 
Did you completely submerge the sensor in the cleaner and let it sit for awhile? Could be the MAF is getting clean enough, but not entirely clean. What's the CEL?

 
http://www.subarutunersofmaine.com/forum/index.php?topic=5567.0

See here for details on how this saga started. So I've gone, say, 6mos with it running fine, save for having to clean the MAF again every once in a while, especially after a heavy rain. On top of what's in the above thread, here's what's happened in the past month or so:

About a month ago: Oil light flashed instantly, and the engine "shuttered" real quick at the same time. Did this twice in one week, checked the oil, and I was down about 3-3.5q. Yes, I really am that stupid. Anyway, topped it off, seemed fine, no problems.

A couple days later: Backed the car into a spot at work, tagged the exhaust on the curb. Hard enough to make me go "Oh raisin!" and dent the tip. Runnah thought maybe I had tweaked an O2 sensor. But again, even through my stupidity, the car seemed to run great.

Yet another couple days later: CEL comes back, again after a heavy rainstorm. Cleaned the MAF, dumped a can of Seafoam in for the hell of it, reset the ECU and voila, no more CEL. Yay!

Until last week, the car was running like a champ. Then we got more rain, and the CEL came back. Cleaned the MAF, reset the ECU, rinse and repeat, but with no results this time. Thought I had it since I went out to mess with it tonite, finally bought a real air filter to replace that K&N, and found the airbox was not on right. Alas, no love.

Now I'm at the point where I'm starting to get scared that one of my stupid moves has cost me an engine. But, the damn thing is running exactly like it did when it was just a dirty MAF to begin with. The only difference at all I have noticed is that instead of waiting 50-75mi to come back after I reset the ECU, the CEL is coming back immediately. This is what's leading me to think the MAF is just done.

I haven't pulled the code yet since it started again, but I'm going to see if our garage won't do me a favor (they owe me enough) and read it for me tomorrow.

 
I'm pushing Runnah to buy the WRX RallyXI has for sale, so I can borrow his.
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i've got 2-3 lying around but since your not pushing for runnah to buy my car i guess i have none :violent5:

 
Are you still seeing lousy gas mileage? Lousy mileage + a lean code is usually an indication that the O2 sensor is bad or you have an exhaust leak. Lousy mileage generally means your car just thinks it is running lean, which points to a post combustion issue. Better mileage generally means your car is actually running lean, which points to a pre combustion issue.

 
Moved and changed the thread title.

Had my buddy scan the code today, and it came back as P0031 (can't remember the exact details on this code). After poking around on NABISCO, it would appear this is related to the O2 sensor in the manifold.

http://forums.nasioc.com/forums/showthread.php?t=1563960&highlight=p0031

Thoughts?

Are you still seeing lousy gas mileage? Lousy mileage + a lean code is usually an indication that the O2 sensor is bad or you have an exhaust leak. Lousy mileage generally means your car just thinks it is running lean, which points to a post combustion issue. Better mileage generally means your car is actually running lean, which points to a pre combustion issue.
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I think mileage is pretty close to what it was before, but I'm not 100% positive. I've reset the CEL so many times in the past week, haven't been able to track a full tank. Not sure it really means much at this point, either.

 
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