lambda sensor

[Harlequin]

how much can a faulty one effect fuel economy?

[spider]

A fair bit as it will use this to determine mixture depending on the content of the exhaust.

[Harlequin]

replacement time then - looking at one for £20 from the bay of fleas (new)

edit: pre mot emissions tested and it scored an awesome 4.9......

[spider]

replacement time then - looking at one for £20 from the bay of fleas (new)

edit: pre mot emissions tested and it scored an awesome 4.9......

that's a bit too much.

Check the airfilter is clean and (sometimes overlooked) the actual air intake piping before / after the filter. A kink / blockage here will have the same effect as a bad filter. No different to a manual "choke" in effect which was only a butterfly to restrict intake air really.

[Harlequin]

airfilter been replaced as has sparks/ht leads and coil pack , and it made little difference taking the pipework off after the airbox (its hard plastic anyway)

[spider]

OK.

It was worth mentioning it as although not that common a partly blocked air intake (more common on a diesel but can happen to petrol engines) can really upset it as its struggling to get enough clean air, similar effect to a choked filter.