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Mercedes CLA Hybrid High Voltage System Error

My 2021 Mercedes CLA hybrid is throwing a high-voltage system error. There's a persistent error code stored, the engine cuts out randomly, and engine power drops noticeably when it runs. I'm leaning toward a battery drain, maybe a defective battery pack. Could cable damage or a faulty voltage sensor also be at play?

4 comment(s)

Sounds like a headache! I had a similar issue with my CLA, not sure of the exact year. High-voltage system warnings are never fun. Did you check the 12V battery first? Sometimes a weak auxiliary battery can cause all sorts of weird electrical gremlins in these complex systems. Is the car still under warranty?

Good point about the 12V battery. I did check it, and it seemed okay, but maybe I need to load test it properly. It is definitely something to consider. But wouldn't a dead 12V battery present different symptoms? What was the fix in your case? Was it a straightforward battery replacement?

Mine ended up being a faulty voltage sensor throwing off the whole system. Cost me to diagnose. Of course, a heavily discharged or defective high-voltage battery can absolutely trigger the same error, so it's best to get it checked out by a pro. I wouldn't mess with the high-voltage system yourself. Seriously, are you sure you want to risk that?

Thanks for the insights. I took it to a certified workshop. They found a faulty voltage sensor, just like you suggested. Repair including the part and labor came to around 290€ Appreciate the help!

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