Second Lambda query...

[Liam]

Out of interest, does it actually have any thing to do with they way the car fuels? My 51 plate VTS doesn't have a second Lambda and isn't particularly good on fuel. I've read, in a few places, that it's only to check if the Cat is working.
Can anyone enlighten me?

[brosnan]

Yeh it is there to make sure the emmisons are good after the cat. the lamba you got on the mani is the brains

[Liam_]

The second lambda is only there for diagnostic purposes - i.e. if it thinks the CAT is broken, it puts the engine management light on. It doesn't affect how the car runs in any way.

Try replacing the first lambda (in the exhaust manifold) and clean the MAP sensor up.

[Liam]

Thanks dude.

[stevyj]

I don't have a second lambda either but still get 35ish mpg on a run