Focus Diesel Injector Drift Compensation Error

Yeah, sounds familiar. I had similar issues with my old 2012 Opel Astra. 'Drift compensation' is basically the ECU learning and adjusting for slight variations in the fuel injectors over time. If an injector is failing, it can't compensate anymore, hence the error and rough running.

So, what did you do? Could the injector just be cleaned, or did it need replacing?

I tried injector cleaner in the fuel at first, but no luck. A proper clean might work, but the mechanic said on my Astra the injector was kaput. The error code and rough running came back quickly, so I ended up getting it replaced. Bite the bullet and take it to a garage, it will save you a lot of headache in the long run.

Thanks for the advice. Took it to a shop, they confirmed a defective injector. New injector fitted, and the quantity drift compensation reset. Cost 515€, but runs smooth now.