AntD6

Sorry, I don't have any further information. I suspect that when it failed in one of the previous years someone made some changes to the Engine Management to try and get it to pass. The mechanic just said he restored the settings to standard and everything was fine.

MOT sorted....garage checked with Autel which showed that nothing had been reset when garage who exchanged Lambda sensor last year.... reset and passed with flying colours.

My 2013 Octavia 3 has just failed with slightly similar CO figures. This is the 3rd failure in 3 years. First year Lambda sensors were cleaned, last year new lambda sensor. Really annoyed it failed this year as tester says no exhaust leak so possibly plugs need a change! I run it on Shell e10 petrol always and car is serviced every year. Plugs have done 25K miles. Could it be an injector that is causing the problem?