Truma Combi 6E - Intermittent Fault

Discussion in 'Motorhome Chat' started by maz, Nov 1, 2012.

  1. maz

    maz Funster

    Jan 26, 2011
    Out there somewhere
    Thought I'd post about my recent experience as others might find it useful if they encounter something similar.

    Starting about a month or so ago I was getting an occasional fault whereby the boiler would make the 'jet engine' noise for maybe 30 seconds and then abruptly cut out with a steady red light showing on the control switch. Switching it off and waiting for a few minutes enabled the boiler to be restarted and apparently function normally. This was happening on hook-up with the electric only setting selected. Not too bad if it did it in the daytime but very annoying in the middle of the night. :Angry:

    I rang Truma for advice and they suggested that I send the printed circuit board to them for analysis as it would have retained a log of the fault codes. As I live in the van it wasn't practical for me to send off the PCB to Truma and wait for a result without any heating or hot water. They then suggested that I find a service engineer who had their computer software that could read these past fault codes. After many phone calls to all kinds of dealers and mobile engineers, I realised that this was worse than looking for the proverbial needle in a haystack - no-one had the software. I was therefore stuck with waiting for the boiler to fault again and then reading the fault code ......

    Before this, I had no idea about the need to look for a fault code when a problem occurs - a series of 8 flashes from a red LED on the boiler itself under a cover plate. The flashes are either short or long, like Morse Code. If you restart the boiler, the fault code stops flashing. To get at the boiler I had to dismantle the innards of a kitchen cupboard. Then I was unable to remove the cover plate (it was awkward to reach as the boiler was end on and apparently there is a knack to it). However, I worked out that by holding a small mirror by the hole in the cover I should be able to read the code the next time it faulted.

    While I waited for the fault to recur (because of course it wouldn't appear to order) I searched the Internet and found just one reference to the exact same problem that I was experiencing. Turns out that earlier versions of the Combi PCB were not compatible with some battery chargers. From time to time the charger would send a voltage spike that tricked the boiler into thinking it was faulting and it would shut down. Later versions of the PCB had been revised so that this was no longer an issue.

    After a few days, the boiler faulted again. After much grovelling in the cupboard, I was able to read the fault code which turned out to be number 26 on the Truma list (link to full list at the end of this post). Sure enough, the one that referred to replacing the PCB with the latest version. So I was able to restart the boiler and arrange for an engineer to change the PCB. In theory, this should have been straightforward. However, once the board had been changed, the boiler refused to start at all and there was no power to the control switch. The fault code this time was number 46 on the Truma list - which covers quite a few possibilities! In case there was a problem with the new PCB, the old one was refitted but the fault code 46 was still flashing and the boiler still would not start. I was now worse off than before as I had no heating or hot water (other than my emergency fan heater) and was on a site with no shower block! :RollEyes:

    The engineer was as dismayed as I was but managed to work out that the fault was now with the combustion air motor. Probably had a dodgy connection within it that was disturbed by the PCB change. So now the combustion air motor had to be changed as well ......... Thankfully, all this comes under the Truma warranty.

    Today the new motor was fitted and (touch wood) the boiler is working fine again and hopefully it will stay that way. However I shall no doubt be paranoid about it faulting again for some time. :Eeek:

    List of Truma Combi 4/6E fault codes:
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