My Cinq seems to be using alot of petrol and was wondering if it was cos a knackered lambda sensor?

I just serviced the car and I changed both parts of the exhaust. The Red injector light on the dash comes on now and again and am I right in thinking that this would indicate a knacked lambda sensor?

So if i changed the lambda sensor would i get a better MPG like i used to when i first got the car?

Also why does the car use more petrol if the lambda sensor was gubbed?

if you take the car to get the ecu read it'll tell you whats up with the car (if anything)

Edit:

Oh and yep the lambda sensor is one of the things which the injector warning light could indicate, and if its been disturbed when removing/refitting then it could well cause it to be playing up

hope this helps slightly,
Cheers

To add to Ghosts post, the lambda sensor detects the unburnt ratio of air and fuel going through the exhaust system. If its not working, the ECU cannot adjust the mixture to be as lean as possible while still providing decent performance - it just runs as rich as the ECU will allow to make sure there is enough fuel being fed into the system.

an emmissions test will tell u if the lambda is knackered.. cheap test too...