Mot fail 8x more co2

Hi all, took my jimny for its mot on Saturday.
Failed on emissions.
All was fine at idel but on the fast idel the co2 shot through the roof and iirc the lambada sensor reading dropped.
Hydro carbons was excessive to.
Ideas?
Car has been stood since January.

I've dropped 20mm of redex into the cylinders, new correctly gapped plugs, air filter. Had oil change the week before
Hoping that and a good high rpm run down the m62 will sort it.
It had a new lambada (top) last year.
Mot guy thinks something is over riding the lambada. No other sensors is there?
It's the g13bb engine.
Thanks

I'd check for vacuum leaks and put a new lambda sensor in.

exhaust leaks will cause that as well