Thanks for your reply Tony.I was under the impression that all cats have to come up to a certain standard these days,I wonder how inefficient a cat has to be % wise before it causes the mil light to come on.The owner was desperate to use the vehicle so she's had it back for 4 days now and the light has stayed off but I'm sure she will be back at some point as we did'nt actually do anything to cure it. Cheers Dave.