Abarth 500 MOT emissions failure

[Charlotte44]

Hello,
My abarth 500 (2009) went in for an MOT yesterday and failed on the emissions test. Results were as follows:
Fast Idle Test:
Co: Max 0.2, actual 1.727
Hc: Max 200, actual 137
Lambda: min 0.970, actual 0.970

Second fast idle:
Co: Max 0.2, actual 1.089
Hc: Max 200, actual 146
Lambda: min 0.970, actual 0.997

Natural idle:
Co: Max 0.3, actual 0.702

I was wondering if anyone had any suggestions for what is causing the problem? I’ve had various different suggestions from the cat, to the lambda sensor/ spark plugs. The car has also been remapped to 181bhp (wasn’t me that did the mapping), so could this be the cause of the problem?
For a bit of context, the previous owner who had it through the last MOT had the cat and lambda readings tested in Jan because a warning light was coming on. The garage he took the car to said they couldn’t find any issues, so he took it back to the place he got it from, and they re-did the mapping. After that he had no more issues.

I don’t know how much of that information is relevant, but I would very much like my car to pass it’s MOT (preferably without me having to sell a kidney to do so), so any suggestions will be greatly appreciated!

Thank you, Charly

[Bungleaio]

Did you try it with the sport button? Sport mode has a different map.