You can also get an idea of "pre cat" gas figures by checking the emissions before the cat lights up.
on February 8, 2009, 10:31 pm, in reply to "Re: VW Golf - Failed MOT on emissions"
If 02 sensor is switching ok, and it's not a "false switch" (system has adapted) then CAT failure.
If system has adapted, then by clearing them, you will "see" a reaction in the 02 sensor.
But you should be able to look at fuel trim figures to get an idea if its a false switch or not.
Regards
Dave
You can trim a sheeps wool many times, but you can only fleece it once !
Message Thread 
VW Golf 1.4 AHW 2000 - MOT emission failure CO 0.8% HC 400 # - Ian Staples February 8, 2009, 7:55 pm
« Back to index | View thread »