Alfa-less and lost.
AO Silver Member
Join Date: Jan 2003
Location: United Kingdom
Re: Emissions fail - high lambda
I could be completely wrong here, but I thought the MOT test just compares the Lambda value from before the Catalytic convertor to the one from afterwards, so it will report a fail if your cat has failed (or is missing), air is leaking in between the two, either of the probes are failing. You could end up replacing 4 probes and not improving the problem if it is due to a leaking exhaust.
Engine ignores lambdas until it reaches full operating temp - so allow 5mins.