NCT Failure - High CO

Just back from NCT, failed on high idle CO levels, limit is 0.20% my reading was 1.59%

Exhaust is Milltek with sports cat, I also put standard airbox with K&N panel back on.

All other readings within acceptable values...

Low idle
(759 rpm)
CO 0.12% Limit 0.30%
HC 24 ppm

High idle
(2887 rpm)
Lambda 1.00 Limit 0.97 to 1.03
CO 1.59% Limit 0.20%
HC 81 ppm Limit 200 ppm

Any ideas on how I can get the CO levels down?

Cheers,

Steve

I'm wondering is it normal for your low/high idle figures to be so drastically different?

I would have thought that such a good figure on the low idle test would have spilled over onto the high.

You might just have to whack on the standard exhaust and then see how she fares - I know its not the most favourable option because you have the sports cat installed but it might be the most effective option.

Hope you get it sorted and pass!

Adam

Thanks Adam, the high idle is where the tester holds it at a certain level I think, low idle is just tickover.

I might put a bottle of Dipetane in at the next fill up and see if that makes any difference.

Had same problem last week with my legacy but worse, it turned out to be the lamda sensor even do I was within the lamda limits in Nct, so might be worth checkin it with diagnostics.

Lambda sensor is the first thing I would check..

Is your car standard/mapped? On what ECU?

I'll get the Lambda sensor checked then, thanks

Car was mapped by JGM, EcuTek.