Hi keith,

I know Alan very well and respect his opinion, I don't know Mark but from what I read I also respect his opinion, However I think any opinions or comments in answer to a post as long as they are valid are OK even if someone else has already posted simmilar, at least then you can form a veiw based on this.

With regard to your subject matter, first and foremost I would be confirming the lambda sensors functionality. From your post and the information you provide it seems obvious to me that the lambda sensor is suddenly failing causing the system to react to a false lean condition. your fuel trim figures also support this.

What make was the new sensor? was it genuine? who fitted it? did they actually test the old one before replacing?

Chances are once you sort this out you will then have to tackle the original fault as like most garages there was probably nothing wrong with the original sensor and they have just made it worse "Cos thats what the scanner said it was".

Just my thoughts,

Mike