Hi all,

00 Fabia 1.4MPi, 60k miles, failed car test at the weekend with lambda reading of 1.347 or thereabouts. Just scanned it with Vag-com, got the attached result. Any opinions on what's buggered?

High lambda means that there is too much air in the exhaust. Either there is a leak where air is getting drawn into the exhaust, the air is not been correctly measured going into the engine ot there could be an air leak where unmeasured air is going into the engine. Another possibility might be that the lambda probe(s) are reading inaccurately and the mixture is being weakened as a result.

Your picture really doesn't tell me a lot, can you post any fault codes from the engine?

Ta for the reply. Unfortunately my version of VAG-COM (or more accurately the cable I have) is not finding any fault codes. The test did show that Hydrocarbon content was fine.

For some reason I'd understood that high lambda was overfuelling - is it the opposite?

This my understanding:

Lambda is the air:fuel ratio. For ideal combustion the optimum ratio is 14.6:1 (stoichometric) which is equivalent to a lambda value of 1. If the air was in ratio of 29.2:1 the lamba would be 2, hence if lambda is over 1 it is weak or too much air, and less than 1 it is rich not enough air.

Is it not actual air/fuel ratio divided by stochiometric air/fuel ratio? So a positive value would indicate that the actual air/fuel ratio is higher than stochiometric and that you are correct.