Mk2 emissions fail

[John&Luke]

Hi looking for your advice. Just had a 1.8 mk2 fail it’s MOT on high CO2 at idle. Is this likely to be a duff lambda senor???

Any advice welcome?

[John&Luke]

Wanted to bump this posting as advice needed.

The garage has run a ‘cleaner’ through the car and it’s still failing. ☹️

My thought process would be a faulty water temp sensor therefore sending a duff signed to the ECU or Lambda sensor?

Help please,

Thanks j

[MXRod]

I always do an "Italian tune up " before the test and the co hardly registers

[blackyb]

Could be a number of things, did you give her a good healthy spirited drive before the test as in blowing the cobwebs out.

[John&Luke]

Thanks guys,

Getting the car today so will look to see if any fault codes are showing, if not will check the exhaust and vacuum hoses then an italian service as suggested.

[GlennyGills]

I'll bite, what's an Italian service ?

[John&Luke]

So no fault codes coming up on the diagnostics.

Fail was fast and second idle test
High CO high HC, low lambda

New plugs, filters and leads ordered from AutoLink, the only obvious is that two of the HT leads look a bit fraded and not ideally. However plugs look pity clean.

Wondering if it’s down to simple under use not warm enough for the cat to get working.

Any more suggestions please???

Italian Tune Up = get her a good thrashing to burn off any deposits is my understanding

[MXRod]

I'll bite, what's an Italian service ?

A spirited drive using maximum revs , helps to warm up the cat , and blast crud out of the exhaust system .
Not quite rev the nuts off , but close

[blackyb]

Italian Tune Up = get her a good thrashing to burn off any deposits is my understanding[/quote]

Got it in one, a poor burn can cause the high readings so its worth a set of plugs and ht leads.

[Mazda Mender]

Zorsts and cats hold water which is a build up of condensation thats why they rust from the inside out, even more so if they are stood and just run to tick over every now and then, if the cat is holding water it will never get to temp and give a fail , you have heard of "blow the cobwebs out" well in this case it is heat and blow the water out.
the issue is centering around the cat on the fail.
M-m