Topic

My MGF 1.8i (X reg) with 110K on the clock has failed the MOT om emissions on CO Hydrocarbons and Lambda sensor!

On fast idle test the results were:
CO 2.7%
HC 237
Lambda .93

What should I test / change first?

When the tester tested your emissions did he block off the other tailpipe.
You can get air sucked in by this pipe and it fools the testing probe. This is particularly the case for the TT Mk.7 exhaust.

Sundance

They have tested my car for the last four years. I have had the Daytona on for at least three!
I don't know but will ask.
To be fair it does have a slight falter on initial acceleration so I suspect something isn't right.

It could be a few things.
Dodgy lambda sensor
Failing catalytic converter
Faulty ECU Temp sensor
As well as the usual Plugs, airfilter, timing...etc.

Just an update on my emissions issue!
I changed the Lambda sensor, in fact changed the manifold and downpipe as lambda threads in manifold were shot!
This pulled the Hydrocarbons and lambda sensor into pass but CO was still twice the required level. Tried cat cleaner which made a slight difference, so just waiting for a new cat to arrive and then hopefully pass MOT!