Clio running rich

[Mertin]

Just got my 172 running a sports cat through MOT, just. 0.200 CO allowed and scraped by at 0.199 red hot

I have checked lambda using rs tuner and it seems to graph ok on idle, could it still be knackered and worth a change?

Also checked coolant sensor and is reading true so shouldnt be running on cold map

 

[Pegasaurus Rex]

Mine ran rich, stank of fuel. Lambda looked to be responding correctly on RS tuner. I had a brand new OE Lambda in stock so chucked it in anyway. Sorted the problem out immediately. Guessing they seem to start ‘going off’ before competently shitting themselves and chucking a fault code

 

[Mertin]

Forgot to mention I had 3 spare lambdas sitting, threw one of them in and checked and graph seemed to be the same.
That isnt to say they were both faulty or past their best like you say
Just ordered a new one anyway and be keen to throw it onto the tester out of curiousity and see what difference it has made

 

[Brigsy]

Might just be due to sports cat, they can be borderline for mot