Hi all.
My sons stilo 1.6 2002 has failed the mot on the emissions test.
When he collected the car the engine light was on & the car was running lumpy with a lack of power. He had the same lack of power & light on problem about a year ago & after checking with my obd meter found it was two of the coils. I replaced the coils & all was well, until now.
If one of the other two coils I didn't replace packed up during the mot would that lead to high readings for the emissions test?

The readings are.

Fast idle test -
co level = 2.04 fail Max 0.30

Hc level = 331 fail Max 200 ppm

Lamda = 0.961 fail min 0.970 max1.030

Second idle test
co level = 2.174 fail Max 0.30

Hc level = 185 pass

Lamda = 0.957 fail

Natural idle test
Co level = 2.87 fail max .50

The car passed on engine speed & temperature tests.

Thanks for any help.

I'd find out what the MIL fault code is telling you

Find out what the misfire is, try pulling out low voltage connector to each coil with engine on tickover to see if one of them makes no difference and then swap over that coil with a good cylinder to see if the fault moves with it. If it stays then check your plugs

With a misfire then emissions will be very rich which is what you have

The code was 302, misfire on cylinder 2. The plugs were changed about a year ago & have done about 6,000 miles.
I've pulled the ht lead off cylinder 2 & it made no difference to the cars running so no-2 is where the problem is. I'll try swapping the coils tomorrow.

Just an update.
It was the coil on no-2 cylinder that caused the misfire. I bought a new one, replaced it & the car passed the emissions test.
When he drove the car to the mot station for the first test it was running fine, what a bloody coincidence that the coil packed in during the mot.
Three coils now replaced, only one left to go. At least it should be easy to identify next time.
Thanks for the help DC5.

Good stuff! Thanks for the update