[Vwdiesel] TDI Oxygen sensors?

[David Cook]

Can anyone tell me what the two sensors (one right in
front of the Cat converter and one right behind it)
do?

When I was talking to the exhaust guy, I mentioned
them and he had never heard of an oxygen sensor on a
diesel.  

What do they actually measure?  They must be comparing
something before and after the cat, but what?  What
would the computer do if the cat were removed and they
were just attached to the straight pipe that will be
put in there?

This is a '96 TDI Passat.

Thanks,

David


David Cook
Red '86 Cabriolet Diesel Powered
Red '90 g60 Corrado 
Brown and White '78 Westy Campmobile "Bear"
and others in various states of disrepair
Pictures here: community.webshots.com/user/superdave5599

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