Unusually High Co at Idle - Peter D
Had an MOT on my ‘last of the production’ Volvo 240 SE Estate Passed no problem but I noticed that the Co at idle has risen from its normal 0.1% or so, on previous MOT’s to 0.39%, still a pass but a lot higher. High speed measurements were 0.1 and only 6PPM Lambda 1.00 Spot on. Any ideas what may be causing this increase. Plugs are not due yet, Air Filter Clean and runs and ticks over perfectly. Thanks Peter
Unusually High Co at Idle - Sooty Tailpipes
Have it tested somewhere else and compare as many readings as you can, just like wheel alignement, it varies from place to place, and on the temperature and prior driving style etc...
Unusually High Co at Idle - Altea Ego
As J says, an italian tune up just prior to the test would probably knock this back down to its previous levels again

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