Webasto fault codes

[Skylark]

The resident engineer at my marina has just installed a Webasto 3500 heater on my Oceanis 361. After about 4 starts over 2 Saturday's the switch is now displaying fault code 12 which according to the two sets of documentation supplied with the kit is either "heater lock-out" or "set point generator (interupt / short circuit)". There isn't a detailed fault diagnostic list so I don't know where the problem is likely to be or how next to proceed. Webasto website points technical queries to its authorised dealers. When you buy a heater kit from a chandler, who ever tells you about an authorised dealer!!!!

I've, of course, asked the marina engineer to take a look but we boat owners do like to know what's going on, don't we.....

I'd appreciate any useful fault finding / resolution advice. Many thanks in advance.

 

[FullCircle]

David see reply to this identical post on Scuttlebutt. Please try not to cross post, gets confusing, and is not considered good form hereabouts