Mercedes Viano generator issue

Sounds familiar. I had a similar issue with my old Vauxhall Astra, although it wasn't the same as your Viano. Same symptoms though: battery low warnings, weak lights, and eventually an engine misfire because of the electrical issues. Did you check the serpentine belt? A slipping belt can cause the alternator to underperform. Also, how old is your battery? Sometimes a weak battery can mask alternator problems.

Serpentine belt seems fine, tension is okay and no visible wear. The battery… that's a fair point. It's not exactly new, but it always seemed to hold a charge. Could a dodgy battery really wreak this much havoc? Could it be the starter motor instead? I really don't want to replace the alternator if I can avoid it.

A weak battery can definitely put extra strain on the alternator, potentially leading to its premature demise. While the starter motor could be a culprit for the poor starting, the other symptoms point more towards the charging system. Given the error codes and flickering lights, I'd say the generator is the prime suspect. Probably best to get it properly diagnosed at a workshop before throwing parts at it.

Thanks for the insight! Took your advice and had it checked out. You were spot on – the generator was indeed defective. Ended up costing me around 960€ for the alternator replacement. At least the Viano is back on the road now. I appreciate the help!