felixmeyer48

GLK Auxiliary Battery Gremlins Anyone Seen This

My 2013 Mercedes GLK with a gasoline engine is throwing some weird errors. I'm getting a battery malfunction message on the speedometer. I pulled the codes, and there's indeed a battery error stored. I've also noticed the engine is a bit sluggish to start sometimes and I'm getting some general electrical weirdness. I'm suspecting the auxiliary battery isn't charging properly. Anyone else experience this, and if so, what was the fix?

4 comment(s)

I encountered a similar situation with my old Volvo XC90. The symptoms you describe sound like the auxiliary battery wasn't holding a charge. Have you checked the auxiliary battery voltage while the engine is running? Also, have you checked the charging system, like the alternator and wiring?

Thanks for the reply. I haven't put a meter on it yet while running, but I did check the resting voltage and it seemed low. Regarding the alternator and wiring, are there any specific points I should focus on when inspecting them?

Yes. Check the alternator's output voltage under load to make sure it's within spec. Also, carefully inspect the wiring harness, especially the grounding points and connectors for the auxiliary battery circuit. Look for corrosion or loose connections. Given the symptoms, a professional diagnosis might be a good idea to avoid further issues and fix the problem correctly.

Appreciate the insight. Sounds like it's time to get it checked out professionally. As suspected, the auxiliary battery was faulty and not holding charge, mechanic confirmed the issue. Ended up costing me around 290€ for a battery replacement. Car electronics working fine now and the engine start is much smoother.

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