From cold the engine runs fine until it warms up, then it developes a misfire (Code reader indicates P020, which points to cylinder 1 misfire). If I stop the engine and restart, the misfre goes until the next time I start from cold. Lately this has been showing up the engine management light. I was all set to buy a new injector yesterday when a guy stopped me (turned out he was a diesel fitter) and said it was more likely the wiring harness, this made me walk away and rethink. The car has done 87k miles and is up to date with its servcing and there are no recalls logged on the car.
Is this more likely a wiring fault or should I replace the injector?
Thanks in advance.