Q: Failed emission test, code P0071

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Emission test did not pass so I replaced the ambient air temperature sensor and went back. Still did not pass. What am I missing here?

My car has 88582 miles.
My car has an automatic transmission.

Hi, thanks for writing in. The code P0071 is set when the AAT sensor IAT sensor and the ECT sensor do not correlate to each other after the vehicle has not been started for at least 480 minutes. One of the three sensors is not sensing the correct temperature. You need to scan the computer after the engine has sat overnight without starting it and look at the data of the three temperature sensors and see which one is not the same as the others. Then test and replace that sensor and clear the codes. If you would like help with this, consider having one of our expert automotive technicians come to your home or office to look at and diagnose these issues for you, and make any repairs as needed.

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