One other issue is corrosion of the pins or socket and moving in and out can
fix the issue.
The low current through these sensors does not keep them clean.
This is not just on boilers seen it in all sorts of equipment with
connectors unfortunately. I doubt if they are gold plated are they!
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"John Rumm" wrote in message
o.uk...
Just in case anyone is getting the same error:

Odd one on a friends boiler (Vaillant Ecotec 824+ combi). Turn it on from
cold, and it goes through a moment of self test before reporting fault
code 76 "main heat exchanger over temperature". Which is quite an
achievement for a cold boiler that has not even lit the burner yet ;-)

So I popped the cover off, had a fiddle with the connectors on the
temperature sensors on the pipes connecting to the input and output of the
main HE. Basically just to check they were seated properly (to be fair
they did not feel loose the touch). Then I turned it on again, and this
time it all sprang into life normally. So probably just a lose connection
or even a bit of condensation in a connector (the boiler had been
relatively unused for a couple of months).

So I figured we could count that as a false positive, so went into the
installer mode[1] menu and erased the fault code history.

[1] The default installer code is 17 for many Vaillant boilers.




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/