C70 MOST Bus Failure

Sounds like a headache. The MOST bus is notoriously sensitive. Have you checked the physical connections of the control units? A loose or corroded connector can cause all sorts of weird issues. Also, have you tried a hard reset by disconnecting the battery for a while? Sometimes that's enough to clear out temporary glitches. Which control units are throwing errors?

Cheers for the reply. Yeah, I've visually checked most of the connections I can easily get to. I did disconnect the battery briefly, but maybe not long enough. As for specific error codes, there's a bunch pointing to the audio module, the navigation unit, and some communication errors on the MOST bus itself. Is there a recommended time for the battery disconnect?

A longer battery disconnect might help, give it at least an hour. But with multiple modules throwing errors and the symptoms you're describing, it's very likely a component failure within the MOST bus. Since you mentioned you are familiar with automotive protocols, I'd recommend connecting it to a diagnostic computer that is able to perform a MOST ring break diagnosis. If you don't have access to one, it's probably best to visit a shop. From experience with similar issues, expect the repair cost to be around 1000€.

Right, understood. Thanks for confirming my suspicions. Looks like a trip to the shop is in order. I was hoping to avoid it, but I don't have the proper diagnostic tools to pinpoint the faulty module. Better to bite the bullet and get it sorted properly. Appreciate the advice!