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My check engine light just recently came on around 80K miles, right after I filled up my tank. My Tacoma is a 98 4 cyl. 4x4. The OBDII scan says the engine is running lean. The guy at Advanced said that this may be the O2 sensor burning out. My question is; is there anything I can do before buying a $180 part that may also fix the problem? Basically it's not necessarily the O2 sensor right? I have noticed a decrease in gas mileage over the past few months and especially as of late. Also does anyone know where I could get a cheaper O2 sensor? Thanks guys,

Ben
 

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GeauxTaco said:
My question is; is there anything I can do before buying a $180 part that may also fix the problem? Basically it's not necessarily the O2 sensor right?
Yeah, post up the actual code that was scanned. P0130 or whatever.

If the O2 sensor does need replacing, Gadget has the real Denso ones for $90. Not the overpriced generic ones that don't work right that Advanced sells.

http://www.urdusa.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=6000&Category_Code=
 

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Try the cheap and easy route first.
Clean your MAF sensor with plastic safe, non-residue, electronic contact cleaner, then reset the computer by pulling the ECU fuse.
This worked for me twice so far. Tacomas dont like dirty MAF sensors.
Tim
 

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GeauxTaco said:
My check engine light just recently came on around 80K miles, right after I filled up my tank. My Tacoma is a 98 4 cyl. 4x4. The OBDII scan says the engine is running lean. The guy at Advanced said that this may be the O2 sensor burning out. My question is; is there anything I can do before buying a $180 part that may also fix the problem? Basically it's not necessarily the O2 sensor right? I have noticed a decrease in gas mileage over the past few months and especially as of late. Also does anyone know where I could get a cheaper O2 sensor? Thanks guys,

Ben
Aha. Are you experiencing any physical problems or was it just the light? Has the light come back after getting reset?

You say it came on right after filling the tank. Did you run out of gas by any chance? If the vehicle runs out of fuel, the air–fuel ratio goes lean and DTC P0171 is recorded. The light will stay on until you have it reset.

Take a look at that pdf that Mike posted, lots of good info there.
 

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Discussion Starter #7
yeah

No physical problems, just a decrease in gas mileage. The light comes on even after I reset the ECU fuse. I ran out of gas once before, which was last year, I don't see a correlation with this past trip.
I'm just gonna clean the MAF sensor, put some fuel injector cleaner in it and hope for the best. If that doesn't work than I'll just have to try replacing the O2 sensor with one from Gadget.
Thanks guys.
 

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My buddy is experiencing something similar. It gives the PO171 code and includes Bank 1 with the code read. I cleaned the MAF for him and that seems to help for a couple weeks. He's running a s/c and I suspected he was running the engine (driving down the road) before letting it warm up a bit. But he says no, he's letting it warm up a bit.

I'm going to go through the 9 page pdf file above and see what else I might try but do you or anyone else have some suggestions for a s/c engine that throws that code?
 

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DriftinCO said:
My buddy is experiencing something similar. It gives the PO171 code and includes Bank 1 with the code read. I cleaned the MAF for him and that seems to help for a couple weeks. He's running a s/c and I suspected he was running the engine (driving down the road) before letting it warm up a bit. But he says no, he's letting it warm up a bit.

I'm going to go through the 9 page pdf file above and see what else I might try but do you or anyone else have some suggestions for a s/c engine that throws that code?
Has he done the URD fuel system upgrades? The s/c pumps in more air and needs more fuel than the stock system can deliver and will run lean unless you help it out.
 

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GeauxTaco said:
My check engine light just recently came on around 80K miles, right after I filled up my tank. My Tacoma is a 98 4 cyl. 4x4. The OBDII scan says the engine is running lean. The guy at Advanced said that this may be the O2 sensor burning out. My question is; is there anything I can do before buying a $180 part that may also fix the problem? Basically it's not necessarily the O2 sensor right? I have noticed a decrease in gas mileage over the past few months and especially as of late. Also does anyone know where I could get a cheaper O2 sensor? Thanks guys,

Ben
Do you have mods, i.e., deck plate or intake or high flow muffler. For some reason My computer won't learn the new settings and throws the same code
whenever it feels like it. This also happenned after I put a high flow muffler on my passat.
 

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GeauxTaco said:
PO171 - system too lean

That's what the print out says from the scan.
That's a MAF sensor not the O2 sensor. Try cleaning it like the other guys said. If it doesn't work, buy a new one.
 

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I threw that same exact code after every fill up when i'd really get on the pedal. Ended up being a dirty MAF sensor thanks to my damn oily k&n filter. Cleaned it, reset the ecu and never had a problem since.
 

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You Guys Rock

Hey just wanted to thank you for these posts im new to the forum , I am having the same code on my truck right now po171 and will try cleaning the MAF tommrow, wish me luck , thanks Robb/ 8noojeep
 

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Same thing happened to me all I did was take my filter off spray injector cleaner throught the tube real good with the engine running it helps to have a buddy that can rev it up a little and start the truck back when you kill it but do this real good then have the the error erased. The Mass air flow sensor gets dirty and starts to fail sending a false error to the ecu. I did mine 2 and half weeks ago and it hasn't come back on yet. Good luck. Also as your vehicle gets older you start losing gas mileage but adding stuff like after market filters and performance mods just speeds up the process. Try running a few tanks of premium gas and add the cleaner to the tanks and see if it doesn't improve a little bit. Also watch your brands of gas mine runs better on BP than anything else. Hope this helps.
 
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