Dennis,
The "tool" from NAPA -"Spark plug opening thread chaser" is marked on one end 18 MM other end is 14 MM. I guess this is the correct tool I've had for several years now. Just forgot about it. Hopefully this will work.

Dennis

Dennis Jowell
Scotch Hollow Farm
Newbury, Vermont 

> On Oct 2, 2015, at 2:44 PM, Dennis Haynes <d23haynes57@hotmail.com> wrote:
> 
> The O2 sensor thread is the same as an "18mm" spark plug like in older
> Fords. The Vanagon spark plug is a 14mm thread. 
> 
> Dennis
> 
> 
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Dennis Jowell
> Sent: Friday, October 02, 2015 2:44 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: How to remove O2 sensor
> 
> Rich
> Is the thread on the O2 sensor the same as a spark plug? Looking through my
> tools I did find a spark plug thread chaser. I can't remember if I used it
> for the sensor or not.
> I think I did because I never did anything with any spark plug threads on my
> Westy. Can you confirm that the threads are the same?
> 
> Dennis
> 
> 
> Dennis Jowell
> Scotch Hollow Farm
> Newbury, Vermont 
> 
> 
>> On Oct 2, 2015, at 10:16 AM, Richard Koller <brvkoller@gmail.com> wrote:
>> 
>> Dennis, 
>> I forgot to mention that I had to restore the threads in the O2 bung with
> a thread chaser ( if my memory holds, I used a spark plug thread chaser )
> after removing the sensor. I've done this a couple times and it has worked
> out each time and I was able to reuse the O2 sensor with no problem.
>> Rick
>> 
>>> On Fri, Oct 2, 2015 at 9:43 AM, Richard Koller <brvkoller@gmail.com>
> wrote:
>>> Dennis,
>>> I had this same problem and I heated the cat at the junction where the O2
> sensor screws in with MAPP gas. Then quickly slipped my 22mm box end over
> the disconnected sensor wires and was able to break it free. It would be
> better as others have said to use the dedicated O2 sensor socket. Heat was
> essential however in my case.
>>> Good luck.
>>> Rick Koller
>>> 
>>>> On Thu, Oct 1, 2015 at 12:37 PM, Dennis Jowell <dennisjowell@gmail.com>
> wrote:
>>>> I just started to replace my O2 sensor on my 2.2 wbx. No,luck using my
> wrenches . Everything is rusted together. The catalytic converter is only
> about a year old. Is there a better way to remove the sensor? Should I use
> my touch to heat the sensor ? Any ideas would be great. I might get to
> Quebec yet just have to get this done.
>>>> 
>>>> Regards,
>>>> Dennis
>>>> 
>>>> Dennis Jowell
>>>> Scotch Hollow Farm
>>>> Newbury, Vermont
>>