Hi there, I am sure I have read about this before, but have no forum search so here it is,
My 3dr had 10%CO for mot and was a failure, It passed last year, and I have altered nothing. After a run the plugs are black, and it does spit black soot out of exhaust, I tried connections on rear sensor on head with WD40 no difference, Any one any ideas, I have no misfires although the car is a bit hesitant to rev, which I presume is due to mixture. I think it maybe one of the sensors gone down, but would appreciate any advise before I start changing them

Darren