>It's grounded -- either from the wire or the device itself is shorted/not
>generating voltage.  It's got a little better ground than the ECU does, so
>you're seeing a zero reading as -0.2 volts (the difference between the two
>grounds).
>

David

my digitool shows .2 to .8 range but during every cycle I also show a slight
negative value. I had my ecu
refurbed and tested(thumbs up)  by Darrel B and have a new O2 sensor. I
guess that leaves grounds as the issue. Is there a particular ground that
would be the likely culprit

Ed
Reno, NV
87 GL