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P0171 Info 2008 Corolla


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#1 BobLevine

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Posted 19 February 2012 - 06:55 PM

Was wondering about a decline in mpg but no real bad performance.

Then got a check engine light P0171. Checked Google before going to my dealer, and learned that many Gen. 9 Corollas had a black intake manifold gasket that dried out and let in outside air leaning out the mixture. A new orange gasket was put out with a TSB.

Dealer changed gasket and performance really improved along with about 3 more mpg.

The code readout for P0171 from Auto Zone didn't mention the gasket. Suggested MAF sensor or big vacuum leak.

Hope this is useful to others who may get this MIL code.

Edited by BobLevine, 19 February 2012 - 06:55 PM.

#2 crypticlineage

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Posted 19 February 2012 - 08:07 PM

Glad to hear the problem was solved, could have been a real PITA without accurate diagnosis. However, this is not a mistake with the code itself. The bad gas mileage is always in some way related to the mass airflow sensor. The code that engine threw (P0171) points to incorrect ratio of fuel/air due most likely to a dirty MAF sensor. In this case it was due to vacuum leak.

Only Toyota knew about the gasket problem. Stuff like this can drive you crazy. You could have replaced the MAF sensor and experienced no improvement.

#3 cirrus

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Posted 20 February 2012 - 02:17 PM

After dealing with the same code the past 6 months on my 2005 LE(110K) the dealer decided the gasket and to be done too. It was taking about 4 weeks to throw the code which I'm at right now. We'll see if that fixes it....keeping my fingers crossed but have this bad feeling I'll be seeing that CEL on again as they seemed to race right to the gasket with little diagnosis...more so because I mentioned a TSB for the gasket being a possible problem. Mine ran great....excellent fuel mileage before the gasket change...no difference after. Maybe it was a tiny leak.

#4 BobLevine

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Posted 23 February 2012 - 04:55 PM

After dealing with the same code the past 6 months on my 2005 LE(110K) the dealer decided the gasket and to be done too. It was taking about 4 weeks to throw the code which I'm at right now. We'll see if that fixes it....keeping my fingers crossed but have this bad feeling I'll be seeing that CEL on again as they seemed to race right to the gasket with little diagnosis...more so because I mentioned a TSB for the gasket being a possible problem. Mine ran great....excellent fuel mileage before the gasket change...no difference after. Maybe it was a tiny leak.


A tech said the gasket was a prime offender resulting in the TSB.

Hopefully, your warning light will stay off.

#5 Papa Bear

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Posted 23 February 2012 - 06:37 PM

Is Toyota using GM intake gaskets ?? .... B)

#6 cirrus

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Posted 24 February 2012 - 08:35 AM

Hopefully, your warning light will stay off.


Fingers and toes crossed..... :D

#7 GeoK

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Posted 01 December 2012 - 09:21 AM

Had the same problem on my '07 S. Replace with gasket. Much bettor performance. Too soon to check MPG omprovement.