Q: My check engine light just turned on mid drive and I began noticing a high pitch hum only while accelerating...possible issues?

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The car drives fine no real stand out issues other than the faint hum. Does not do while in park or in low gears. Starts just as I shift into last gear around 3rpm and 45mph. Sound gets higher in pitch the faster I go making it less noticeable.

My car has 127000 miles.
My car has an automatic transmission.

Hello, There are a number of possible causes for creating a humming sound as you describe, however the most common that would also be correlated to RPM change would the a failing alternator. When the alternator is not working properly, this may result in the battery quickly losing charge and the car losing all power as you have described. You may also notice a whining sound as a result of the bearings inside the alternator begin to fail. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your charging system.

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