The car went in with a suspected cracked piston, mechanics did the engine swap as it was cheaper than reconditioning. Got the car back and the EPC & Engine lights continued to pop up and send the car into limp mode, took it back to the mechanics and they determined it must be a faulty engine after doing some testing on it. They forced the engine dealer to give them a new one which was compression tested etc... before it was put back into the car. I got the car back and the lights came back on again within five minutes of leaving the mechanics.

They then sent it to an auto electric specialist who examined all of the wiring from the engine to the ECU and said there was no problem with the electrics and concluded it was either the engine (which surely it couldn't be after two different engines) or the ECU but it wasn't presenting any fault codes.

I'm at a complete loss now, the car is currently sat at the Newstead Austral VW dealership having the faulty Takata airbag swapped out. I'm looking at $880 to do an ECU kit swap but even then it may not be the issue. I've always used premium fuel.

Does anyone know of any other potential causes of this?

I am currently in a terrible financial position due to changes at work, so I just need to get this sorted but no one can give me a definitive answer and I can't afford to spend more money on parts etc... if it's still not going to resolve the issue.


Current issues:
Rough idling (Engine seems to flutter but revs remain stable)
Engine light comes on followed by EPC
Poor power delivery and juddering

Parts that have been replaced:
Coil packs
sparkplugs
Engine x2
Various sensors (which the original mechanics still haven't given me the list for but replaced for free)