Question 1

Error W 42 H: Truma CP plus control panel displays a warning icon (heating system operating parameter out of range)

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 a 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.

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 41 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`	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.	DIY Safe

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