lambda sensor low mpg

[bigmonmulgrew]

Hi
Ive just read in another post that a dodgy downstream lambda sensor can cause low mpg
Ive also read a dodgy lambda sensor can cause the odd misfire.
Ive had a fault code come up a couple of times complaining of misfire but after resetting it it takes a long time to come back

Is there any way i can confirm its the lambda sensor without changing it, they are a bit pricey

 

[Matt e]

take it to a garage and get it on a diagnostics machine they can check it

 

[bigmonmulgrew]

I do have an obd ii reader, would i be able to find out with that?