My CEL light came on and stayed on last week. I was razzing it up a dual carriageway.

I've been told it could be the lamda, or the neutral position switch.

Re the lambda, what does it do and how much is the Subaru unit ?

Is it true that a faulty one could affect mpg ?

 

Sort of, actual standard cars don't have a Lambda sensor at all, they have an oxygen sensor from which Lambda can be inferred (it cannot measure lambda at all, only exhaust gas Oxygen).

The Oxygen sensor outputs a voltage dependant on the amount of Oxygen in the exhaust and from this the engine managment controls the fuelling around Lambda one. I don't know how much it costs from Subaru, but correct fit items from the specialist websites are typically £80-100.

Yes, they typically fail reading lean, so the engine managment adds fuel to its limit to compensate, this does nothing for the already poor fuel economy!

Simon

 

Cheers Rookie. Appeciated.

AndytJ