MOT Fail - Emissions

[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

[Carolyn]

These work well:

https://www.cats2u.co.uk/3267-18

[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

[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.

[frogger]

A leak anywhere on the exhaust can also give such CO readings.   I had a TTE exhaust where the left tip fails, and the right tip passes and every year had to remind the MoT tester!  Sure enough the only issue was how well the left tip was sealed to the back box.

The manifold to cat joint is a prime area for a bit of leaking - but that tends to also lead to an EML light with time (assuming a non-import with a post-cat sensor), so if no EML a leak is less likely unless it is post-sensor.