Normal reading from pre cat lambda?

[Diagro]

Hey.

What's the normal readings?

Mines jumping all over.... from 10 to 900! So random

Anyone got an idea?

 

[MartinR]

Iirc the pre cat does jump up and its the post cat sensor that runs pretty much equal.

Any jump in that for a very short period of tim throws the eml.

Someone in the know shall explain better lol