My local Subaru dealer here in Cyprus informs me, that the ECU holds the previous 24 hours of engine run information from all of it's sensors in memory. If there is a problem then the garage can download this information to find the cause of the fault. Allowing them to escape a warranty claim if you have been abusing the engine. Does anyone know if this true?

Doesn't sound very true to me - it certainly will memorise sensor faults, but I am pretty sure that datalogging is not a key part of the JECS ECU. Twenty-four hours of datalogging is an awful lot of data. And if it only stores peak values how does that prove abuse.

They're tugging your chain mate!

Trout

Your local Subaru dealer is trying to frighten you. The ecu only retains fault codes for a limited period.