Car help , high emissions

[Alee]

Here's a strange one that has 2 garages lost.
The patient is a Seat Leon Cupra 1.8 turbo.
Runs perfectly with no issues other than high co levels at fast idle (1.46)
Treatment so far includes a new lambda and 2 new cats.
Car Has been scanned but shows no fault codes . All sensors, pipes , plugs etc have been checked, everything appears to be spot on !
So far we have two large bills from 2 garages and still have no answers .
Any suggestions ?

 

[proactive]

Take it to AA Silencers for diagnosis.

 

[Lucy]

Was it one of the models that needed an alteration following the scandal? My Seat did.

 

[Lucy]

And I assume (if it's diesel) it still has its DPF?

 

[Alee]

Petrol