Avantime Fault Memory Lock

I had a similar issue with my Avantime, although it wasn't consistently showing. Is it possible your battery is getting a bit weak? Undervoltage can cause all sorts of weird electrical gremlins in these computerised systems. Have you checked the voltage when the engine is off and when it's running?

Undervoltage, huh? I haven't actually tested the voltage directly, just visually inspected the battery terminals. If the voltage is low, would that cause a persistent 'fault memory lock'? Is the control unit throwing a tantrum because it's not getting enough juice?

It's not a definite cause, but it's a common one and a good place to start, as it can cause issues with memory. Low voltage can scramble the signals the control unit receives. If you're getting error codes, it might be worth having a workshop run a proper diagnostic. It could save you a lot of time.

You were spot on! Checked the battery voltage, and it was indeed low. Replaced the battery, cleared the codes, and the error is gone. Workshop confirmed the same, total cost 240€. Thanks a bunch for the suggestion!