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Owners Handbook :
Troubleshooting Combi Gas Heater Guide
(H)
FAULT CODE
CAUSE
REMEDY
W 255 H
Heater has no 12V power supply
Ensure that the 12V power supply
is available
No connection between heater and
control panel
Make connection between heater
and control panel
W 302 H
W 418 H
Low voltage. Battery voltage is too
low < 10.0V
Charge battery. If necessary,
replace old battery
W 303 H
W 411 H
Risk of low voltage. Battery voltage is
too low < 10.4V
Charge battery
W 401 H
Summer mode with empty
water container
Switch heater off and allow it to cool.
Fill boiler with water
W 402 H
Warm air temperature exceeded:
Not all warm air ducts are connected
Check whether the 4 warm air ducts
are connected
Warm air outlets blocked
Check the individual outlet openings
Circulated air intake blocked
Remove the circulated air
intake blockage
W 407 H
No 230V operating voltage
Restore 230V operating voltage
230V fuse defective
Replace 230V fuse
(see Combi operating instructions)
W 408 H
No gas supply in Mix mode
Check gas supply.
See fault # 507 (electronic heating
continues in Mix mode)
FAULT CODE
CAUSE
REMEDY
W 412 H
Window above cowl open
(window switch)
Close window
E 507 H
E 516 H
E 517 H
Gas cylinder empty
Replace the gas cylinder
Gas cylinder or quick-acting valve in the
gas supply line closed
Check gas supply and open valves
Gas pressure regulation system iced up
Use regulator heater (EisEx)
Butane content in the gas cylinder
too high
Use propane. Butane is unsuitable for
heating, particularly at temperatures
below 10 °C.
Combustion air infeed or exhaust
outlet is sealed
Inspect openings for obstructions
(slush, ice, leaves, etc.) and remove any
obstructions
Gas pressure regulation system faulty
Inspect / replace gas pressure
regulation system
E 607 H
Max. number of fault resets reached
Wait 15 minutes and reset fault
E 621 H
Room temperature sensor or cable faulty
Inspect the room temperature sensor
cable, replace if faulty
E 624 H
Frost Control heating element has
a short circuit
Disconnect heating element plug
from electronic control unit.
Replace heating element
E 632 H
Overheating protection has
been triggered
Reset overheating protection
(see Combi operating instructions)
If these measures do not remedy the malfunction or if fault codes are displayed that you cannot find in the
troubleshooting guide, contact Truma Service.
