MOT Fail - Emissions

Started by valguss2001, December 3, 2025, 09:16

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valguss2001

Hi Guys

My frog failed it's MOT yesterday on Emissions and also a rotting rear subframe. Subframe I think I'm OK on and will be calling TCB for pricing in the new year.
For the Emissions, the garage said that the catalyst has failed and it looks like it's newer than the header, so might be an aftermarket smaller one. Earlier this year, I also knocked out the pre-cats.

My question is, should replacing the catalytic converter sort this and does anyone have any recommendations for a new cat?

Cheers

Tom

2001 silver roadster called Mr Bug

Carolyn

Perry Byrnes Memorial Award 2016, 2018.  Love this club. 
https://www.mr2roc.org/forum/index.php?topic=63866.0

Gaz mr-s

This might not be practical, but a product like Cataclean can make a significant improvement.  My partner's car has a 200 cell cat which has been on for several years. Her car failed & the testing station said 'new cat', - they didn't venture a cat-cleaner.  Cataclean sorted it, - passed easily.  You want to run the engine hard when you add it.

Change the subframe, make an MOT appt' & drive the car some miles before it.



 

valguss2001

Thanks both

Suspect it will be better in the long run to replace the cat. It's going to be off the road for a few months so can save up some pennies for a new one; also shiny new chrome pipes. I wonder if a previous owner replaced the cat with a non type approved one.

Cheers

Tom
2001 silver roadster called Mr Bug

Ardent

As readings are not that far out. Could an  exhaust leak be enough to cause the fail?

How much of a leak is needed to fail?

Carolyn

A good cat will read about .01 to .02, so reading close to .3 means it's at the upper limit and is close to end of life.
Perry Byrnes Memorial Award 2016, 2018.  Love this club. 
https://www.mr2roc.org/forum/index.php?topic=63866.0

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