The O2 sensor has a pair of wires that operate the heater portion (so
that it warms up quickly, faster than just from the exhaust of a cold
engine). I don't recall what circuit feeds them, but if they shorted,
you may not have, say, voltage to the coil. The ECU is another
obvious possibility. Start by checking all your fuses: shorting out
the heater portion OUGHT to simply kill a fuse, regardless of what
circuit it is on. However, I had an '87 on which the harness smoked a
foot or two away from where the O2 sensor leg joins in when the sensor
failed, so I'm not certain that it's protected.
It is a notorious problem... The O2 sensor heater circuit is most
definitely UNFUSED on a lot (perhaps all?) of our 16Vs; I've heard of
many a good wiring harness that melted down because those bloody heater
wires shorted out... VW must've been passing out free crack the day they
designed this particular circuit.
There's a bunch of O2 notes over here:
http://www.nwlink.com/~vdb/vw/Engine/oxysensor.html
(check out the warning towards the bottom).
I don't recall what else is on that wire either, but fuel pump sounds
right... Sorry Brian, but it looks like you need to get out that
multimeter and see what state your wiring harness is in... not fun, but
with the Bentley you should be able to figure it out. :(
Cheers,
Oleg
