+3 more
MAXIA, ONTOUR, PrestigeHobby Heating
(Caravans, 2026 Model Year)
View official manual on manufacturer's site ↗Master Troubleshooting & Diagnostics Matrix
| Error Code / Indicator | Symptom / Meaning | Possible Cause | Step-by-Step DIY Fix | Suggested Actions |
|---|---|---|---|---|
W 42 H | Truma CP plus control panel displays a warning icon (heating system operating parameter out of range) | An operating parameter of the heating system has reached an undefined status; the device continues to operate. | Select the warning icon using the adjusting knob/pushbutton, then press it again to read out the warning code shown (format: W for Warning, a code number, then H for Heating). Once whatever caused it has been sorted, press the knob/pushbutton once more to return to the normal setting mode. If it hasn't been sorted, use the reset button instead - the panel will stay in its warning state and keep the icon showing, though every other connected device carries on working as normal. | DIY Safe |
E 112 H | Truma CP plus control panel immediately goes to Malfunction mode and displays a malfunction error code | A genuine malfunction has occurred in the heating system (format: E = Malfunction, code number, H = Heating). | Once the underlying cause is sorted, press the adjusting knob/pushbutton and the affected device will restart on its own. If it isn't sorted, use the reset button instead - because of a short internal lag in the connected equipment this can take a few minutes, and the panel may drop back into Malfunction mode again if the fault's still there.
Every other connected device keeps working throughout. | DIY Safe |
N/A | Truma Combi Gas heating develops a fault partway through the combustion process (e.g. running low on fuel) | A fault has occurred in the gas combustion process. | The system automatically falls back to electric heating. If you're running in mixed mode, you'll need to sort out what's causing the fault first, then use the control panel to turn the heating off and on again to clear it. | DIY Safe |
N/A | An error code appears on the heating display after a 230V mains interruption while running on electric power (with the 12V supply still on) | The 230V mains supply has been interrupted while the heating is running on electric power. | This clears itself - once the 230V supply comes back, the heating restarts automatically with its previous settings and the error code goes away on its own. | DIY Safe |
N/A | FrostControl safety/drain valve indicates a risk of sub-zero temperatures | — | The valve automatically drains the boiler's contents via the drain outlet - no action needed unless you want to prevent the automatic drain, e.g. by keeping the installation area heated.
Under excess pressure, the system will perform intermittent pressure equalisation via the safety valve.
You can also open it by hand to drain the water system yourself, say to clean the tank or before winter storage. | DIY Safe |
Frequently Asked Questions
Q: How do I read a warning or malfunction code on my heating control panel?
A warning icon means one of the heating system's operating parameters has drifted outside its normal, defined range - the device keeps running regardless, and the icon clears itself once that parameter settles back within range. Press the control knob/pushbutton to display the current code (shown as a letter + number, e.g. 'W 42 H' = Warning, code 42, Heating) - check this against the error list in your Truma documentation to find the cause.
Once the cause is resolved, press the control knob/pushbutton again to clear it. A malfunction code (shown as 'E' instead of 'W') means the control panel has gone into Malfunction mode and the device has stopped - once the cause is resolved, pressing the control knob/pushbutton restarts the device. If the cause hasn't been resolved, use the 'reset' button - if it still isn't cleared, the malfunction will reappear once the control panel finishes its internal lag/restart period (this can take a few minutes).
Other connected devices can still be operated while one device is showing a warning or malfunction.