Q: My check engine light comes on then leaves randomly

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The check engine light comes on then leaves randomly. Sometimes it takes just a few hours and sometimes a day. I get the same codes for the MAP sensor (changed it twice) and the fuel tank pressure sensor. The car does not buck anymore nor does it behave abnormally. The only thing that bothers me is the throttle being tweaked to prevent too-low idling. This causes the car to move more without using the pedal (i.e letting the car move by itself now makes it hit 7 MPH quickly from a complete stop, which was not how it was before).

My car has 146000 miles.
My car has an automatic transmission.

Generally, the check engine light comes on when something fairly serious is going on with the vehicle. This can happen for many different reasons such as a faulty mass air flow sensor, a faulty O2 sensor, a bad catalytic converter, bad spark plugs or spark plug wires and many other reasons. Due to the wide range of possibilities for the check engine light to come on, the best and most efficient way to narrow down the scope of what may be causing this is to have the vehicle hooked up to a scanning tool to download any potential fault codes that may have registered in the computer. This will allow a mechanic to determine more specifically what to look for in diagnosing your vehicle. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle to determine what may be causing your check engine light to come on.

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