Engine code 7e8 in a GMC Terrain indicates the knock sensor has detected vibration from the engine. The knock sensor deteCTS-Vibrations in the engine, but it also notices vibrations that a normal human could not notice. These vibrations can damage the engine if it keeps up. With the sensor not working then You run the risk of damaging the engine. If the sensor is putting up an error code then You need to take the car to a mechanic, as if You leave it alone then You will have issues.
Robert R
July 30, 2020
Engine Code 7E8 in a GMC Terrain indicates the knock sensor has detected a vibration from the engine.
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