Lenz Posted September 23, 2020 Share Posted September 23, 2020 I have a one year old Benimar Mileo 243 motorhome with Truma combi 6. Until this week it has worked fine but three times now the warning W255H has popped up and the hot air distribution fan has suddenly ramped up to maximum speed. The warning is for loss of 12V supply or loss of communication between the Truma panel and boiler. The 12V supply was 'on' so I suppose the problem is to do with the connection between panel and boiler. The bizarre thing is that the warning has occurred when the boiler is 'off' and the only way to stop the racing fan is to pull the 12V supply fuse. The boiler then operates normally until switched off when the fault occurs some time afterwards (e.g. half an hour later). Anyone come across this strange behaviour before and know the way to rectify the problem? Mike Link to comment Share on other sites More sharing options...
Keithl Posted September 23, 2020 Share Posted September 23, 2020 Mike, Is your one year old van still under warranty? If so contact the dealer to arrange getting it fixed. Keith. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted September 24, 2020 Share Posted September 24, 2020 Lenz - 2020-09-23 8:14 PM ...Anyone come across this strange behaviour before and know the way to rectify the problem? Mike Truma’s advice regarding the W255H warning on a CP+ control-panel is here https://www.truma.com/uk/en/faq/faq-warning-w-255-h Warning W 255 H appears in the display of the CP plus panel – what should I do? The heater does not have 12 Volt power supply or there is no connection between the heater and the CP plus control panel. The power supply to the heater may have been interrupted by switching off the vehicle control panel (not the Truma heater control panel). The control panel is used to control all other functions in the vehicle and it also switches the power supply for the consumers in your vehicle on or off. - In this case turn on the control panel in your caravan to reestablish power supply for the heater. - Once the power supply is guaranteed and the warning is still present, check the cable connection between the heater control panel and the heater. Have you searched on-line for comments on this? If not, the results from a GOOGLE-search using “truma w255h error code” as the search-term can be read from this link https://tinyurl.com/y4nqakot The first thing to confirm (as mentioned in some of the on-line comments) is that the cable linking the Combi to the CP+ control-panel is securely connected at both ends. Advice in the Truma ‘flash code’ listing is as shown in the image attached below. If the cable is not the culprit, a fault with the CP+ panel and/or with the Combi could be causing this peculiar behaviour. You could try asking the Truma technicians about this https://www.truma.com/uk/en/service/customer-service but - as Keith has said - the Benimar dealer that sold you the motorhome really needs to investigate the problem iniitially, and accurate diagnosis may be tricky if the fault only manifests itself sporadically. Link to comment Share on other sites More sharing options...
Lenz Posted September 24, 2020 Author Share Posted September 24, 2020 Keithl - 2020-09-23 8:22 PM Mike, Is your one year old van still under warranty? If so contact the dealer to arrange getting it fixed. Keith. it is but I try to rectify faults myself where possible. Thanks for your interest though. Mike Link to comment Share on other sites More sharing options...
Lenz Posted September 24, 2020 Author Share Posted September 24, 2020 Derek Uzzell - 2020-09-24 7:48 AM Lenz - 2020-09-23 8:14 PM ...Anyone come across this strange behaviour before and know the way to rectify the problem? Mike Truma’s advice regarding the W255H warning on a CP+ control-panel is here https://www.truma.com/uk/en/faq/faq-warning-w-255-h Warning W 255 H appears in the display of the CP plus panel – what should I do? The heater does not have 12 Volt power supply or there is no connection between the heater and the CP plus control panel. The power supply to the heater may have been interrupted by switching off the vehicle control panel (not the Truma heater control panel). ... Thankyou for taking the time to respond. I shall follow up the links you gave and will post again when I have a resolution of the problem. Mike Link to comment Share on other sites More sharing options...
Lenz Posted September 27, 2020 Author Share Posted September 27, 2020 After some 'testing' it seems likely that the problem was caused by my switching the fan off manually when also switching off the heating. This may have resulted in the temperature withing the boiler area rising too much and upsetting the electronics causing unexpected behaviour. Simply switching off the heating and leaving the fan on ECO setting to be controlled automatically by the system seems to have solved the issue. Once again thanks for everyone's help. If my solution turns out to be wrong I'll be back! Mike Link to comment Share on other sites More sharing options...
Lenz Posted October 5, 2020 Author Share Posted October 5, 2020 Contacted Truma about this odd behaviour and they said pcb probably needs replacing so van booked in for investigation under warranty. Mike Link to comment Share on other sites More sharing options...
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