Mercedes E Klasse Overvoltage Issues

Sounds like you have a major electrical problem Overvoltage is serious business A heavily discharged or defective car battery can cause this, but it's often caused by alternator failure Start by checking the car battery voltage with a multimeter, both when the engine is off and when it's running What voltages are you seeing Also, inspect the alternator wiring for shorts or damage Has the car battery been replaced recently

Okay, I'll grab a multimeter and check the car battery voltage Where exactly should I measure on the alternator Also, what voltage readings would indicate a problem with the car battery or the alternator The car battery was replaced about a year ago Could a faulty voltage regulator really cause all these issues

Measure the alternator output voltage at the B+ terminal on the back of the alternator while the engine is running You should see around 14V Anything significantly higher than that, like 15V or more, confirms the overvoltage If the voltage regulator is shot, it can definitely cause the problems you're seeing With that many electrical gremlins, and given the symptoms, it's best to get it checked out by a professional They can properly diagnose the charging system and check for any damage to the car ECU from the overvoltage

Thanks for the advice I took it to my local mechanic Turns out the car battery was indeed defective, and the alternator voltage regulator was also fried, causing the overvoltage They replaced both Total cost was 290€ Hopefully, this fixes everything I really appreciate the help