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Q: Does the O2 sensor make the engine check light appear?

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Some times when I turn the car on the rpms are going up and down, and have to turn it off and back on to function right

My car has 144000 miles.
My car has an automatic transmission.

A: Hi, thanks for writing in. To answer your q...

Hi, thanks for writing in. To answer your question simply-- YES, it is very common for the check engine light to illuminate when the O2 or air/fuel ratio sensors are acting up. When the sensor detects an issue inside the fuel manifold, or if the sensors are damaged it will trigger an OBD-II error code to be stored in the ECM. This in turn illuminates the check engine light. The rising RPMss may be caused by one of these components, but the only way to determine which one is to complete a diagnostic scan to pull those error codes and determine the culprit. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to perform the scan for you.

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