Detailed information about the fault codes, their cause and how to fix them can be found in the Operating and Installation Instructions of the Truma CP plus.
Troubleshooting guide (Combi gas heater)
Fault code Cause Remedy
#17 Summer mode with empty water container Switch heater off and allow to cool. Fill boiler with water
#18 Warm air temperature exceeded:
– Not all warm air ducts are connected
– Warm air outlets blocked
– Circulated air intake blocked – Check whether the 4 warm air ducts are connected
– Check the individual outlet openings
– Remove the circulated air intake blockage
#21 Room temperature sensor or cable faulty Inspect the room temperature sensor cable, replace if faulty
Check the resistance of the room temperature sensor.
15 °C – 16.2 kOhm / 20 °C – 12,6 kOhm / 25 °C – 10.0 kOhm
Replace room temperature sensor if faulty
#24 Risk of low voltage. Battery voltage is too low < 10.4 V Charge battery
#29 FrostControl heating element has a short circuit Disconnect heating element plug from electronic control unit. Replace heating element
#42 Open window above cowl (window switch) Close window.
#43 Overvoltage > 16.4 V Check battery voltage / voltage sources such as the charger
#44 Low voltage. Battery voltage is too low < 10.0 V Charge battery. If necessary replace old battery
#45 No 230 V operating voltage
230 V fuse defective
Overheating protection has been triggered Restore 230 V operating voltage
Replace 230 V fuse (see Combi operating instructions)
Reset overheating protection (see Combi operating instructions)
#112,
#121,
#122,
#202,
#211,
#212 Gas cylinder empty
Gas cylinder or quick-acting valve in the gas supply line closed
Gas pressure regulation system iced up
Butane content in the gas cylinder too high
Combustion air infeed or exhaust outlet is sealed
Gas pressure regulation system faulty Replacing a gas cylinder
Check gas supply and open valves
Use regulator heater (EisEx)
Use propane. Butane is unsuitable for heating, particularly at temperatures lower than 10 °C.
Inspect openings for obstructions (slush, ice, leaves, etc.) and remove any obstructions
Inspect / replace gas pressure regulation system
#255 Heater has no 12 V power supply
No connection between heater and control panel Ensure 12 V power supply
Make connection between heater and control panel
Troubleshooting guide (Combi Gas heater) from year of construction 04/2018
Fault code Cause Remedy
#255 Heater has no 12 V power supply
No connection between heater and control panel Ensure 12 V power supply
Make connection between heater and control panel
#301,
#417 Overvoltage > 16.4 V Check battery voltage / voltage sources such as the charger
#302,
#418 Low voltage. Battery voltage is too low < 10.0 V Charge battery. If necessary replace old battery
#303,
#411 Risk of low voltage. Battery voltage is too low < 10.4 V Charge battery
#401 Summer mode with empty water container Switch heater off and allow to cool. Fill boiler with water
#402 Warm air temperature exceeded:
- Not all warm air ducts are connected
- Warm air outlets blocked
- Circulated air intake blocked - Check whether the 4 warm air ducts are connected
- Check the individual outlet openings
- Remove the circulated air intake blockage
#407 No 230 V operating voltage
230 V fuse defective
Overheating protection has been triggered Restore 230 V operating voltage
Replace 230 V fuse (see Combi operating instructions)
Reset overheating protection (see Combi operating instructions)
#412 Open window above cowl (window switch) Close window.
#507,
#516,
#517 Gas cylinder empty
Gas cylinder or quick-acting valve in the gas supply line closed
Gas pressure regulation system iced up
Butane content in the gas cylinder too high
Combustion air infeed or exhaust outlet is sealed
Gas pressure regulation system faulty Replacing a gas cylinder
Check gas supply and open valves
Use regulator heater (EisEx)
Use propane. Butane is unsuitable for heating, particularly at temperatures lower than 10 °C.
Inspect openings for obstructions (slush, ice, leaves, etc.) and remove any obstructions
Inspect / replace gas pressure regulation system
#607 Max. number of fault resets reached Wait 15 minutes and reset fault
#621 Room temperature sensor or cable faulty Inspect the room temperature sensor cable, replace if faulty
Check the resistance of the room temperature sensor.
15 °C – 16.2 kOhm / 20 °C – 12,6 kOhm / 25 °C – 10.0 kOhm
Replace room temperature sensor if faulty
#624 FrostControl heating element has a short circuit Disconnect heating element plug from electronic control unit. Replace heating element
Troubleshooting guide (Combi Diesel heating system)
Fault code Cause Remedy
#111 Room temperature sensor or cable faulty Inspect the room temperature sensor cable, replace if faulty
Check the resistance of the room temperature sensor.
15 °C – 16.2 kOhm / 20 °C – 12,6 kOhm / 25 °C – 10.0 kOhm
Replace room temperature sensor if faulty
#122 Lack of fuel due to insufficient fuel tank filling, tank has run empty and / or vehicle is on a slope Fill tank with fuel. Then fill the fuel line as described in “Initial startup” (see Combi Diesel operating instructions).
#131 No connection between heater and control panel Make connection between heater and control panel
#132 FrostControl heating element has a short circuit Disconnect heating element plug from electronic control unit. Replace heating element
#150 Warm air temperature exceeded:
- Not all warm air ducts are connected
- Warm air outlets blocked
- Circulated air intake blocked - Check whether the 4 warm air ducts are connected
- Check the individual outlet openings
- Remove the circulated air intake blockage
#151 Water temperature exceeded in winter mode:
Water temperature sensor excessive temperature
Warm air outlets blocked
Circulated air intake blocked Switch off appliance and allow it to cool down. Fill boiler with water
Check the individual outlet openings
Remove the circulated air intake blockage
#152 Water temperature exceeded in summer mode:
Water temperature sensor excessive temperature
Warm air outlets blocked
Circulated air intake blocked Switch off appliance and allow it to cool down. Fill boiler with water
Check the individual outlet openings
Remove the circulated air intake blockage
#160 Undervoltage < 10.2 V Check battery voltage, charge if necessary
Short-term immediate measure. Switch off major consumers or start up the vehicle engine until the heater starts to operate (approx. 4 minutes)
Battery capacity inadequate, if necessary exchange old battery
#161 Overvoltage > 16.4 V Check battery voltage / voltage sources such as the charger
#162 Open window above cowl (window switch) Close window.
#164 No 230 V operating voltage
230 V fuse defective
Overheating protection has been triggered Restore 230 V operating voltage
Replace 230 V fuse (see Combi operating instructions)
Reset overheating protection (see Combi operating instructions)
#170 Risk of low voltage. Battery voltage is too low < 10.4 V Charge battery
#255 Heater has no 12 V power supply
No connection between heater and control panel Ensure 12 V power supply
Make connection between heater and control panel
Troubleshooting guide (air conditioning system)
Fault code Cause Remedy
#1 Failure (short circuit or broken cable), room temperature
sensor Contact Truma Service
#2 Ice sensor (inside) triggered Inspect the filter and replace it if necessary
#4 Ice sensor (outside) triggered Keep the air inlets / outlets on the roof free of obstructions such as leaves
#8 IR receiver unplugged or cable broken Check the connection of the IR receiver
#17 Voltage drop at 230 V power supply Check 230 V power supply
