Look at the harness to the distributor. That ground is also the ground
reference for the O2 sensor. Yes the one that is connected to the base of
the plastic oil breather tower.
Replace the ring terminal and relocate to an all metal connection such as
one of the screws holding the fuel pressure regulator and you will be
surprised how many issues disappear.
I suggest a ring terminal with heat shrink attached to stop that wire from
corroding even more.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
HotelWestfalia
Sent: Saturday, April 02, 2011 11:52 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Ground of Oxygen sensor reading 10.6V

Hi to all,
This is a '91 model, 2.1L Vanagon, gas, 2wd, I am using my Digitool and with
a new Oxygen sensor I'm getting 10.6 volts on the "Oxygen sensor ground"
reading.  It started off with (minus) -0.2, and it supposed to be about 0
(zero), which was fine, then very soon it jumped to 10.6 and staying there.
Before I installed the new sensor, the old one was doing the same.
Question; any of you know about this kind of thing? and if yes, what to do
with it?  I'm having 10 mpg with this van.
Most of the things have already been changed, like the wires, plugs, cap and
rotor, temp. II sensor, and now the Oxygen sensor, and the timing is right.

Any ideas?
Zoltan