Hi you helpful friendly folk! I am a fairly new owner of an early 4200 CC and recently fitted a Jaren X pipe and modified back boxes. Not sure if it's related (I didn't drive the car much pre doing this) but got some fault codes coming up from a mechanic friend - P4021 RH catalytic convertor, P4031 LH catalytic convertor, P0102 mass air flow (had a new one fitted recently), and I assume unrelated but P4063 fuel level sensor. So the general thought process is do something with the cats - any advice welcome!