Mot Failure - Exhaust Emissions High Lambda

[treemite]

Hi everyone, this is my first post on this forum.

Yesterday I took my 1996 MR2 in for MOT and it failed on "Exhaust emissions Lambda reading after 2nd fast idle outside specified limits".

The guy who did the MOT told me I had a minor leak at the catalyst joint and the guy at a different garage this morning told me I should get a new lambda sensor.

The readings were as follows -

Fast Idle test:

CO 0.38% (vs 0.3% limit)

HC 59ppm (vs 200ppm limit)

Lambda 1.13 (vs 0.97 to 1.03)

2nd Fast idle test

CO 0.11% (vs 0.3% limit)

HC 21ppm (vs 200ppm limit)

Lambda 1.16 (vs 0.97 to 1.03)

Natural idle test

CO 0.35% (vs 0.5% limit)

The question is - do I get the leak repaired (changing of gasket I think) or get a new Lambda sensor?

The new Lambda sensor is a bit pricey for me at the minute (quoted at £120 fitted) so I was hoping that fixing the leak would solve the emissions problem. Is this likely?

Any advice gratefully received!

[McLovin]

You fix the leak first, and it will most likely solve your issue. The system needs to be air tight, ANY blowing will affect the emmissions.

You are not far out at all on those figures, a duff lambda would most likely give much higher rate of failure than what you have at the moment...

[treemite]

You fix the leak first, and it will most likely solve your issue. The system needs to be air tight, ANY blowing will affect the emmissions.

You are not far out at all on those figures, a duff lambda would most likely give much higher rate of failure than what you have at the moment...

Cheers. That's what I thought was the best course of action.