Ok. Thanks. If I recall, Bosch O2 info I'd read said that atmospheric
air was referenced via the space between each wire and sensor body.
Can't find that info but this mentions similar:   ( I think the
Vanagons use thimble type O2 ?)

http://www.ratwell.com/mirror/www.forparts.com/Bos02update2.html

"Unheated Thimble-type O2 Sensors (LS) ....  Reference outside air for
the interior of the thimble comes from a hole in the sensor shell, or
through the wiring connector."

("Heated Thimble-type O2 Sensors (LSH)" doesn't mention any of this so
I assume it works the same way)

My '88 2.1 has a type of shield that clips onto the O2 body. Could
that block a hole in sensor shell?

I don't think this type is used in Vanagons but....

"Heated Planar-type O2 Sensors (LSF)
Introduced by Bosch in 1997,  .....  Outside reference air is supplied
by a small port in the center of the ceramic strip where the 4
electrical wires connect.   .... "

From a Bosch website page re: construction of Planar type O2 sensors
"Air duct layer. Creates a void for reference air in the finished assembly"

Neil.

On 6/25/14, Dennis Haynes <d23haynes57@hotmail.com> wrote:

> I doubt if at the wire connection itself. How it senses the O2 difference is
> a mystery.

--
Neil n

Blog: tubaneil.blogspot.ca

'88 Westy http://tinyurl.com/c8rlw6p

'81 VanaJetta 2.0 "Jaco"  http://tubaneil.googlepages.com/

Vanagon VAG *Gas* inline-VR Engine Swap Group:

http://tinyurl.com/d7gd5ej