mot failure

[delboy21]

Car failed its mot today on emissions

Fast Idle Test
CO=0.57 Fail
HC=00017 Pass
Lambda=0.99Pass

Second Fast Idle Test
CO=2.16 Fail
HC=00028 Pass
Lambda=0.94fail

Normal Idle Test
CO=0.50

its either my cat or my lambda sensers. Can anyone tell from these readings which it could be? As lambda sensors aint cheap and a new cat for my car is uber expensive.

 

[cupramillo]

If it is the cat could be a good excuse to get a new sports cat
Not sure what it could be though, mine had its MOT 2weeks ago and passed on everything! Well chuffed as ive come from owning 3 fiats (fix it again Tony's) and they cost me an arm and a leg to keep on the road, good bless Spanish/German build quailty

 

[flooky]

get it on vag com and check.

 

[delboy21]

any techies know just by looking at the readings,must be someone in the trade that can tell

 

[m0rk]

It's not the lambda probes... they wouldn't be working right (which they are)

Do you have a cat? that's what I'd replace

pick up a 2nd hand one for not too much

 

[JayFR150]

If it was the lambda sensor your engine management light would come on

 

[delboy21]

thanks mork would you say with your experiance its defo the cat then

 

[m0rk]

it's likely.... however - how well serviced is it? check the air filter, plugs etc - when were they last replaced?

 

[tarzan]

16804 - Catalyst System: Bank 1: Efficiency Below Threshold

P0420 - 35-00 - -
have this fault code and failed mot same as you looks like we have to change cat then