GLK fault memory lock active

I'm officially pulling my hair out! My 2008 Mercedes GLK with a gasoline engine is throwing some weird error. The dash isn't lighting up, but the mechanic says there's a "fault memory lock active." He mentioned something about undervoltage and car electronics. My mileage is at 100732 km, any ideas before I sink a ton into auto repair? Has anyone run into this ECU fault or control unit craziness? What does active memory mean? Am I doomed?

4 comment(s)

Hmm, that sounds vaguely familiar. I've got a GLK too, and I had a similar issue with a persistent error code a while back. The 'fault memory lock active' thing rings a bell. Was anything else acting up, or just the error code? What did they say was causing the undervoltage? Because in my case, it turned out to be a slightly weak battery messing with the car electronics.

Just the error code, that's what's so strange! Everything seems to be running perfectly fine. They mumbled something about the control unit needing to be reset because of the voltage dips, but honestly, it sounded like guesswork. Did your mechanic mention anything about needing to reset the ECU fault or anything like that?

Yeah, that's almost exactly what happened to me. The error kept coming back even after they cleared it. We thought it was some major auto repair job at first. Honestly? Save yourself the headache and just get the battery properly tested and maybe replaced. If that doesn't fix it, then you might have a deeper car electronics issue. But that fixed it for me. Still I recommend going to the shop anyway.

Okay, awesome! Thanks, that's super helpful. I'll get the battery checked out first thing. I took it to another shop, they confirmed the undervoltage issue and cleared the fault memory after replacing the battery. Cost me 240€ in the end, which is a lot better than I was expecting. Really appreciate the insight!

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