Truma CP plus
Official technical documentation and workshop diagnostics for CP plus.
View official manual on manufacturer's site ↗Technical Specifications
Operating Voltage8 V – 16.5 V DC
Power Consumptionmax. 65 mA (100% background lighting) / 6.5 mA – 10 mA (stand-by) / 3 mA (Off)
Dimensions Cutout92 x 103 x 40 mm
Master Troubleshooting & Diagnostics Matrix
| Error Code / Indicator | Symptom / Meaning | Possible Cause | Step-by-Step DIY Fix | Suggested Actions |
|---|---|---|---|---|
W 17 H | Warning Water overheat condition (woc) | Water temperature inside the container has exceeded normal limits | Switch the heater off, let it cool, and top up the water container. | DIY Safe |
W 18 H | Warning Air overheat condition | Either not all the warm air ducts are connected, the warm air outlets are blocked, or the circulated air intake is blocked | Check every warm air duct is properly connected to the heater and none are damaged or kinked, clear whatever's blocking the circulated air intake, and make sure the installation space has enough ventilation. | DIY Safe |
W 402 H | Warning Air overheat condition | Warm air ducts disconnected, blocked, or circulated air intake obstructed | Check every warm air duct is properly connected to the heater and none are damaged or kinked, clear whatever's blocking the circulated air intake, and make sure the installation space has enough ventilation. | DIY Safe |
W 24 H | Low voltage is imminent - battery voltage has dropped below 10.4V | Supply voltage has dropped below acceptable thresholds | Run the engine and check the power supply unit, and any other batteries, are working properly, charge the battery and check its contacts, and fit a new battery if it's old. | DIY Safe |
E 29 H | The FrostControl heating element is drawing too much power | Electrical fault or short circuit in the FrostControl heating element | Must be replaced by an authorized service agent. | Professional Intervention Required |
W 42 H | Window switch detects open window | Window above cowl is open while heater is operating | Close window above cowl. | DIY Safe |
W 412 H | Window switch detects open window | Window above cowl is open | Close window above cowl. | DIY Safe |
E 43 H | The 12V supply is faulty (overvoltage) | Excessive voltage supplied at the appliance 12 V input | Check the 12V supply reaching the appliance while under load - to test it, isolate the vehicle's own supply from both the solar system and the power supply unit. | DIY Safe |
W 301 H | The 12V supply is faulty (overvoltage) | Voltage exceeds safe operating limits | Check the 12V supply reaching the appliance - to test it, isolate the vehicle's own supply from both the solar system and the power supply unit. | DIY Safe |
E 540 H | The 12V supply is faulty (overvoltage) | Input voltage too high | Confirm there's a proper 12V supply under load at the appliance, and check for any stray AC voltage - to test it, isolate the vehicle's supply from both the solar system and the power supply unit. | DIY Safe |
W 45 H | 230 V power supply faulty | Mains supply issue or blown 230 V fuse or overheating protection triggered | Check the 230V supply reaching the appliance. Have a qualified person check the 230V fuse and replace it if needed, and reset the 230V overheating protection (see the Combi's own operating instructions). | DIY Check / Tech Fallback |
W 407 H | 230 V power supply faulty | Mains voltage missing or internal 230 V fuse blown | Check the 230V supply reaching the appliance. Have a qualified person check the 230V 10AF fuse and replace it if needed. | DIY Check / Tech Fallback |
W 164 H | 230 V power supply faulty | Mains supply fault or blown internal T10AH fuse | Check the 230V supply reaching the appliance and reset the 230V overheating protection. Have a qualified person check the 230V T10AH fuse and replace it if needed. | DIY Check / Tech Fallback |
E 111 H | Fault in the electronics | Internal electronic error or unstable 12 V supply input under load | Check the 12V supply reaching the appliance while under load - to test it, isolate the vehicle's own supply from both the solar system and the power supply unit. Contact an authorised service agent if the problem persists. | DIY Check / Tech Fallback |
E 112 H | The flame goes out or isn't detected, is unstable while running, or the gas supply cuts out | Interruption in gas supply or incorrect operating pressure | Check the gas supply is at the correct operating pressure. | DIY Safe |
E 122 H | There isn't enough fuel - the tank level is low, has run dry, and/or the vehicle is on a slope | Fuel tank empty or vehicle tilted preventing fuel pickup | Refill the tank, then fill the fuel line as described under initial start-up in the operating instructions. | DIY Safe |
W 255 H | The heater has no 12V supply, or the heater and control panel aren't connected to each other | Power cable disconnected or control panel bus communication fault | Check the 12V supply reaching the appliance - to test it, isolate the vehicle's own supply from both the solar system and the power supply unit. Also inspect the control panel's cable and confirm the heater and control panel are actually connected. | DIY Safe |
W 302 H | The 12V supply is faulty (low voltage) | Battery voltage has dropped too low | Charge the battery and check its contacts, and fit a new one if it's old. | DIY Safe |
W 160 H | The 12V supply is faulty (low voltage) | Low battery voltage or high resistance on supply line | Confirm there's a proper 12V supply under load at the appliance, charge the battery and check its contacts, fit a new battery if it's old, or switch off any high-draw appliances. | DIY Safe |
E 541 H | The 12V supply is faulty (low voltage) | Input voltage too low | Confirm there's a proper 12V supply under load at the appliance, charge the battery and check its contacts, and fit a new battery if it's old. | DIY Safe |
W 303 H | Low voltage risk - battery voltage has dropped below 10.4V | Battery state of charge is critically low | Run the engine and check the power supply unit, and any other batteries, are working properly, charge the battery and check its contacts, and fit a new battery if it's old. | DIY Safe |
W 401 H | Hot water mode running with an empty water container | Water heating activated while container is empty | Switch the heater off, let it cool, and top up the water container. | DIY Safe |
W 408 H | The gas supply has cut out while in mixed mode | Gas pressure drop or empty gas bottle while operating in mixed mode | Make sure the gas is arriving at the right operating pressure. Start up on gas only, acknowledge the fault, and then change to mixed mode. | DIY Safe |
E 507 H | Gas supply interrupted | Gas supply failure or incorrect pressure | Check the gas supply is at the correct operating pressure. | DIY Safe |
E 607 H | The heater's hit its maximum number of fault resets and is now locked out | More than 4 resets attempted within 15 minutes | Wait 15 minutes, then reset the fault. | DIY Safe |
E 621 H | The room temperature sensor or its cable is faulty | Damaged room temperature sensor wire or loose plug connection | Check the room temperature sensor's cable and its plug connections, and fit a new sensor if it's faulty. | DIY Safe |
E 624 H | The FrostControl heating element has short-circuited | Electrical short circuit in FrostControl heating element | Must be replaced by an authorized service agent. | Professional Intervention Required |
E 132 H | The FrostControl heating element has short-circuited | Short circuit detected in FrostControl heating element circuit | Confirm there's a proper 12V supply under load at the appliance, and check for any stray AC voltage - to test it, isolate the vehicle's supply from both the solar system and the power supply unit. Contact an authorised service agent if the problem persists. | DIY Check / Tech Fallback |
E 632 H | The 230V overheating protection has tripped | Mains heating element overheated | Reset the 230V overheating protection (see the Combi's own operating instructions). | DIY Safe |
E 131 H | The heater and control panel aren't connected | Communication bus cable disconnected or damaged | Make sure the heater and control panel are properly connected to each other. | DIY Safe |
W 150 H | Warm air temperature exceeded | Blocked air ducts or restricted circulated air intake | Check every warm air duct is properly connected to the heater and none are damaged or kinked, clear whatever's blocking the circulated air intake, and make sure the installation space has enough ventilation. | DIY Safe |
W 151 H | Water too hot (heater mode) | Empty water container or restricted warm air/circulated air flow | Switch the heater off, let it cool, and top up the water container. Also check that every warm air duct is connected and unobstructed. | DIY Safe |
E 152 H | Water too hot (hot water mode) | Water container empty during hot water operation | Switch the heater off, let it cool, and top up the water container. | DIY Safe |
E 162 H | The window switch above the cowl is open | Safety switch triggered by open window near exhaust cowl | Close window above cowl. | DIY Safe |
W 163 H | A temperature switch has tripped open | Appliance overheated due to restricted airflow | Let the heater cool down. Contact an authorised service agent if this keeps happening. | Professional Intervention Required |
W 170 H | Imminent low voltage < 11.5 V | Supply voltage dropping toward threshold | Confirm there's a proper 12V supply under load at the appliance, charge the battery and check its contacts, and fit a new battery if it's old. | DIY Safe |
W 423 H | Initial filling is needed (the fill function used at first start-up) | Boiler system unprimed during initial start-up | Trigger the initial fill by setting a heating request for 30°C. | DIY Safe |
W 424 H | Initial filling active | Boiler is currently running initial priming cycle | Don't switch the heater off, or cut its power, while the initial fill is running. | DIY Safe |
E 560 H | Heater will not start (locked after fifth error acknowledgment) | Repeated failed start attempts resulting in lockout | Check the fuel supply reaching the appliance. Contact an authorised service agent if the problem persists. | DIY Check / Tech Fallback |
E 561 H | The heater won't restart - it's hit its maximum number of start attempts and locked out | Operating lock activated due to consecutive failed start attempts | Contact an authorized service agent. | Professional Intervention Required |
E 565 H | The heater won't start; the flame keeps failing to be detected | Fuel delivery issue or air in fuel lines | Check the fuel supply reaching the appliance. | DIY Safe |
E 8 A | The IR receiver is unplugged, or its cable is broken | Infrared receiver connection disconnected or damaged | Check the IR receiver's connection. | DIY Safe |
E 17 A | The 230V supply has dipped | Mains supply voltage drop affecting air conditioning system | Check 230 V power supply. | DIY Safe |