Mercedes GLK Diesel Electrical Overvoltage Problem

I have a perplexing electrical issue with my 2013 Mercedes GLK diesel, which has about 116749 km on it. I keep getting fault codes that point to overvoltage, which seems to be causing other system failures. The battery also seems weak when starting, and generally there are electrical malfunctions. Could a bad battery really cause all of this?

4 comment(s)

Overvoltage on a GLK? I had something similar, though it started differently. Have you checked the voltage regulator? A bad one can cause high voltage, which can damage electronics. Did you see any flickering lights or other weird electrical behavior before the failures?

Thanks for the quick reply. Does the voltage regulator usually fail without warning? If it is the problem, how can I check it before replacing parts?

Yes, the voltage regulator can fail pretty suddenly. It's a common electrical issue. Checking it yourself is tough without special tools. Taking it to a good shop is the easiest and safest way. They can use a multimeter to check the alternator output and see if the voltage regulator is the issue. Ignoring high voltage is risky; it could damage other parts. Be careful.

I appreciate the confirmation about the seriousness of the overvoltage. I took it to a shop, and they found a bad battery causing the overvoltage. The total cost for a new battery and labor was about 290€. Thanks for pointing me in the right direction.

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