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To cut a long story short.. lol.

Emissions light came on and came out on the fault reader as lamba sensor at bay 2 inoperable (after the cat). Replaced lambda and reset the ecu fault and took for my MOT. The result was it failed on emissions but lambda on the print out was a pass. Took for a nice run and realised a slight misfire then the emissions light kicked in.. Bloody coil! Replaced the coil and reset ECU and attempted the MOT retest (thinking that the breaking down coil must have caused the emissions failure) but the retest results were the same for the emissions. Now I have taken the car to a diagnostics garage and they have noticed that the lambda at bay 1 (pre cat) is sticking at .4 during operation and is not switching.
By changing this lambda sensor at bay 1 how likely is it that it will now pass the emissions?
Have anyone else had similar difficulties?

Are pre and post cat lamba sensors the same part numbers? If so, the pre cat lamba will give values that flucuate and the post cat lamba will give a constant reading. If they're the same part numbers you could try swaping them round and this might solve your problem.

Another thing to check for is corrosion in the plugs on the terminals as it is common for the plugs to get water in them sometimes.

Thanks for your reply drewbar, The two lambda's are diffierent part numbers they have different plug entries on them.

I tested the lambda's today and both were reading fine and working. I find it odd how the guy told me that its not working because I saw both lambdas working with my own eyes today.

Now that I know the lambda's are fine what do you think I should try? There are no faults coming up on my dash anymore the car is running smooth but the emissions are still too high.

Thanks

As a cheaper fix, we often put a decent fuel cleaner through the system. The best one that I know of to use is Forte fuel treatment, helps clean out the injectors and remove carbon deposits. Other thing to do is make sure the car is nice and warm before you get go get it tested again as the emisions levels are a little bit lower at full temperature.

Yeah I did put some fuel cleaner in so i will wait till that passes through and try again. What do you think of cat cleaner should I try running some of that through too? If neither of these work would a VAG COM pick up anything if there are no warning lights coming up on the dash board? Thanks

Cant see putting a cat cleaner through the system doing it any harm mate aslong as it compatible with your car. Not 100% sure about what vag com will tell you tbh as i've never used it but it all depends what you've been using to read the fault codes in the first place I guess. Id say that 99% your going to be better off getting it checked using VAG COM rather than universal software as it can sometimes be flawed.