Q: Replaced my upstream O2 sensor. The check engine light won't turn off.

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My check engine light was on so I took it to AutoZone for a diagnostic check. It came out as my bank one sensor one O2 sensor. I replace that and now the truck is running much better. However, the check engine light won't turn off. How is this done? I've tried driving, getting the codes cleared, and disconnecting the battery.

My car has 93000 miles.
My car has an automatic transmission.

When an error code is triggered and stored in the ECU, it needs to be removed by a professional mechanic using a digital scanner; and not a simple code reader. The folks at Auto Zone use the code reader and are not able to clear codes correctly in most cases. However, it is possible that a different code is stored in the ECU, as more than 100 individual codes can trigger the check engine light to illuminate on the dash. I would recommend having one of our professional mobile mechanics come to your location to complete a check engine light inspection; so they can clear the old codes and determine if other faults are found.

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