Toyota Corolla 2000 has code PO171: Air/fuel mixture system lean bank 1. What's

manuel7marin

New member
causing this? I have already resolved this so I thought I would put this question up because many people have the same problem. No answer is needed for this question.
I tried cleaning the MAF sensor but it didn't work. I bought a re-manufactured MAF sensor from Auto zone (they don't sell new ones) and this solved the problem. I had to take the old MAF sensor to them to get a discount. I paid $85 for the re-manufactured MAF sensor, and it would have been almost $150 if I didn't trade in the old sensor. This sensor is located near the air filter. How you reset the code is up to you, I disconnected the battery for 2 minutes. You must drive it around for several miles before you go to the inspection test, otherwise it will fail the test if it has too many codes with NOT READY status.
Be sure that the air filter compartment is tightly locked in place and that nothing is broken and letting air in, as this can trigger this code as well.
I drove it far enough to consume over one full tank of gas and the check engine light remained off. I took it to have the inspection test and it passed and all the tests were in READY status.
 
What it means is that the engine is running lean. There are many possible problems that may cause the air-fuel mixture to be lean: Defective or contaminated airflow sensor, intake vacuum leak, dirty fuel filter, etc. There are certain tests to be performed to find the exact cause of the problem
 
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