Another emissions failure (help!)

[Stevie360]

My P reg 318 failed it's mot on emissions, quite badly. It failed last year (previous owner) but he got a new cat for it and got it passed. This year it's failed again, but when the cat was replaced last year the guy used exhaust paste to get a seal BEFORE the cat. Could this have messed the cat up, because it's only a year old? The lambda readings were just out (1.033 instead of 1.030 max) but the co readings were high (0.586% instead of 0.200% max). Any help would be great cos money's tight right now

[Matt UK]

Thrash it on the way to the test and have then take the readings when everything is as hot as possible. It might help.

[dasherdiablo1]

You'd be surprised what a good blast can sort!!!
I've had a couple of cars fail on emmissions, the testing centre have recommended revving the engine for a good 25 miles and then retesting. It really does work wonders; brought the levels down to well below the limt!