XC70 Knocking Issue

Sounds plausible. Have you tried running a fuel with a higher octane rating? Also, when was the last time you checked your ignition timing? Could be piston slap, too.

Thanks for the suggestions! I haven't tried a higher octane fuel yet. Regarding ignition timing and piston slap, is there a straightforward way to diagnose those myself, or does it require special equipment?

Diagnosing ignition timing and piston slap accurately usually needs some specialized tools. Considering the smoke and error codes, I'd lean towards getting it checked by a workshop. Could be cylinder heads, too. Better safe than sorry!

Okay, I appreciate the advice. I'll take it to a workshop. It turned out to be deposits in the combustion chamber. Repair cost was 425€. Thanks again!