Question 1

Error W 42 H: Truma CP plus control panel displays a warning icon

Accepted Answer

Possible cause: 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.

Question 2

Error E 41 H: Truma CP plus control panel immediately goes to Malfunction mode and displays the Malfunction error code

Accepted Answer

Possible cause: 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.

Question 3

FrostControl safety/drain valve indicates a risk of sub-zero temperatures

Accepted Answer

Possible cause: The FrostControl valve has detected a risk of sub-zero (freezing) 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. Intermittent pressure equalisation automatically takes place via the safety valve whenever the system pressure gets too high.

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	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 41 H`	Truma CP plus control panel immediately goes to Malfunction mode and displays the 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`	FrostControl safety/drain valve indicates a risk of sub-zero temperatures	The FrostControl valve has detected a risk of sub-zero (freezing) 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. Intermittent pressure equalisation automatically takes place via the safety valve whenever the system pressure gets too high.	DIY Safe

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