thank you for the info more reading to be done on my part only trouble is the brain is nearly full

thank you again

Chris

so how does the pcm tell if the emmission is wrong after the cat it only has the post sensor and the fault codes available to the post sensor is limited ie heater fault or bad wiring or slow response.
thanks for the reply

chris

cats £600.00 +vat customer is still thinking about it this is why i was so interested in the hash do not want to make a misdiagnos.
on the same subject why is it not a good idea to test the cat with pre and post sensors .
thanks

chris

thank you for the reply a little more info i checked the connections and i also switched channels the close lines still remained on the post cat sensor i also did a gas check the c0 was high suggests the cat has gone never seen it before .
thanks

chris

hi i am trying to test a cat and would like a little help on the following capture
http://www.theimageboard.com/uploads/94cyn0nm.jpg

in the lower (blue) trace there is a lot of vertical lines what does that mean is it interferance if so how do i clean it up ! thanks Chris