put a digital voltmeter on the signal wire while it's well warmed up and
running.
You want to see the voltage swing from ..
something like .3 volts to .8 volts..
nice range like that.

if it's a much narrower range ..it's sleepy or 'lazy' .
it it's just a steady .5 volts or so ..
it's dead.

if it  looks visually like it's been on there 8 years..
it's due usually.
anti-seize compound on the threads !
and not hyper tight, quite snug and firm , but not super-gorilla tight.
they can get terribly stuck in.
I've even had them gall the threads coming out ....so be careful.

and a special 22mm 02 sensor socket or 22mm tubing nut wrench is often
needed.

Scott
www.turbovans.com

----- Original Message -----
From: "Michael R" <michael@JAMHOME.US>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, June 29, 2011 11:04 AM
Subject: Re: BAD gas mileage and injector service

> Jim Felder wrote:
>> Maybe your O2 sensor has gone out, leaving you in "open loop"
> mode and its
>> notoriously bad gas mileage.
> How would one test
> for that before buying and installing an O2 sensor?
>
> --
>
> Michael Rasmussen
>   http://www.jamhome.us/
> Be Appropriate
> && Follow Your Curiosity