i saw the question was raised a while back, would the sports cat keep the ecu happy in relation to pre and post cat lambda reading and where it would pass an MOT. Has anybody had the sports cat through a the CEL, as mine came on this morning. And its the first time since have the car iv seen this fault code
16804/P0420/001056 - Ross-Tech Wiki
The exhaust doesnt seem to have any leaks. Would a fix for this to have the post cat lambda mapped out when i go in for mapping?