Kuppersbusch convection oven

[ectofix]

I’ve never heard of that company.  They’re not prolific in the U.S. market.

 

All I could come up with was a picture on the German E-Bay website:

 

 

That appears to be a combi-oven from the mid to late ’90s.  I can’t find a manual, so if you say that fault F9 is a boiler sensor, you must already have one.  We’ll go from there.

 

I’ll presume that the boiler sensor in question is for sensing water level in the boiler.  My initial approach on ANY steamer or combi-oven that I work on is to remove and inspect the water level probe(s).  If you find it scaled up, then it needs to be descaled.  Scale can alter the probes ability to sense water properly…whether that being the probe itself or the scale lining the boiler walls.

 

There could be other possible causes to your problem, but I’m not going to write a book about it here.

 

If you find heavy scale on the probe, then I suggest that you find out how long it’s been since the boiler has been descaled.  If nobody knows, then DO NOT attempt a chemical descaling.  There’s probably W-A-Y more scale in there than any chemical can remove.  You’d need to remove the boiler, remove the heating elements…then employ the “hammer & chisel” method of scale extraction.  A shop vac would be handy too.

 

After you’ve done the above, follow up with a proper chemical descaling procedure – making sure you flush it out by filling it to the point of overflowing and draining it THREE TIMES.  After that, run it in steam mode for fifteen-to-twenty minutes, then drain THAT out.