Help
 

I have a Porsche Boxster 2.5 and it has failed the emission test on to high Co. The car has been serviced including fuel filter, plugs, oil, air filter, oil filter and coil packs. In addition to this its had new Cats, new o2 senors and I have cleaned the Air flow mass sensor. There are no error codes coming up, have you any idea why the ecu is providing to much fuel so its pushing up the Co emissions? I have cleaned the air system and I have mixed the petrol with injector cleaner, could this cleaner affect the readings? Please can you help? Thank you
:matchup:

Just in case the injector cleaner loosened up a good amount of carbon deposits, you may wish to try an Italian tune-up on the highway and then take it back in.

Thanks for that but I have tried that and still no joy.

Charles,
Did you ever get any further forward with this query , mine is doing the same
Thanks
Rob

Check the throttle body and plenum jubilee clips. I had mine fail an MOT only to find that a pipe was loose causing way too much air in the system. Tightened it up and it flew passed the MOT.