Yes, it is not a switch, it is a conductivity probe. 

alistair

On 2012-01-08, at 7:11 PM, Larry Alofs wrote:

> If it senses the level, why call it a temperature probe.
>  And why use the term switch to describe two simple metal prongs.
> 
> Larry A.
> 
> 
> On Sun, Jan 8, 2012 at 8:21 PM, Tom Torrella <ttorrella4@comcast.net> wrote:
>> The expansion tank. Next to the pressure cap is a coolant level switch (improperly referee as 'a probe'). See examples @ BusDepot though they don't list the switch. After I had it replaced the problem was solved.
>> 
>> 
>> Expansion tank:
>> http://www.busdepot.com/details.jsp?partnumber=025121403A
>> 
>> Pressure cap:
>> http://www.busdepot.com/details.jsp?partnumber=025121321B
>> 
>> 
>>> What tank has a temp probe???
>>> 
>>> Larry A.
>>> 
>>> 
>>> On Sun, Jan 8, 2012 at 9:02 AM, Tom Torrella <ttorrella4@comcast.net> wrote:
>>>> My 1.9 had same intermittent issue. The probe was replace solving the problem.
>>>> 
>>>> Possibly two issues:
>>>> Air in reserve tank off the water pump.
>>>> Defective temp probe in same tank.
>>>> Also check condition of pressure cap - tight?  leaking?
>>>> 
>>>> TomT