Crossback with a gremlin misfire.

Hi lads and ladettes, Hope all is well.

So my DS3 Crossback has a pesky misfiring issue that I cant get to the bottom of and I’m now nearly £1000 into it and it’s still here.

Started around 3 weeks ago - misfired for around 3-5 minutes one day then sorted itself out. It was fine for the following week then all of a sudden it was a continues misfire. I’ve scanned it with my trusty EuroCar Parts scanner and its throwing these codes; P1338, P1338, P1338P, P1338P.

I’ve taken it to main dealer and they cleared the codes today (after 6 deleting attempts). Car left there fine and then after 5 mins driving it was back. I limped the car back home, turned it off and back on and now its not misfiring but the ‘Engine Fault’ warning is on.

So far I’ve change all 3 coil packs, 3 spark plugs, had main dealer scan and delete, had it serviced etc any I cant get to the bottom of it.

Please someone help or guide me

Usually in this engine (1.2t), compression problems start with cylinder number 2. Did you measure the compression when the problem occurred?