had MOT test today (early) and failed badly on emissions!
CO2 readings very high, nearly double what they should be!
So the K&N will be going back on!
Spoke to Nick at RTech so can swap the old chip back in.
But my questions are what if this doesnt make it read right? What else should I be looking at?
Oxygen(lambda) sensor was changed a couple of years ago as was the CAT.
What other sensors could affect it?