Vaillant Boilers

This diagnostic code indicates how many times the boiler's safety temperature limiter has activated, leading to a shutdown due to overheating. A rising number suggests a recurring issue with the boiler's temperature control.

This diagnostic code displays how many times the boiler has entered a lockout state due to unsuccessful ignition attempts. A non-zero or increasing number signifies a persistent problem with the boiler starting.

The boiler has detected an open circuit in the flow NTC (Negative Temperature Coefficient) sensor. This means the sensor is either broken or its wiring connection is faulty, preventing accurate temperature readings.

The boiler has detected an interruption in the flow temperature sensor circuit. This means the boiler cannot accurately measure the temperature of the water leaving it.

The boiler has detected an interruption in the return temperature sensor circuit. This prevents the boiler from accurately measuring the temperature of the water returning to it.

The boiler has detected an open circuit in the return NTC (Negative Temperature Coefficient) sensor. This means the sensor is either broken or its wiring connection is faulty, preventing accurate temperature readings.

The flow temperature sensor circuit has a short circuit. This prevents the boiler from accurately reading the flow temperature, which can lead to incorrect operation.

The boiler has detected a short circuit in the return NTC (Negative Temperature Coefficient) sensor. This indicates a fault with the sensor itself or a short in its wiring, leading to incorrect temperature readings.

The boiler has detected a short circuit in the tank NTC (Negative Temperature Coefficient) sensor, which is used for domestic hot water. This indicates a fault with the sensor or its wiring, leading to incorrect temperature readings.

The safety temperature limiter has activated, causing the boiler to switch off. This typically happens if the boiler detects an unsafe overheating condition.

The boiler has detected too little water within the appliance, or there's an issue with the water pressure sensor, pump, or its connection. This is a critical safety fault.

The boiler has detected a water shortage condition, indicated by an excessively large temperature difference between the flow and return NTC sensors. This often points to circulation problems.

The boiler has detected a water shortage condition, indicated by the temperature rising too quickly. This typically points to poor circulation or air in the system.

The boiler has shut down because the flue gas temperature has exceeded safe limits. This is a safety measure to prevent overheating of the flue system.

The boiler has detected that the gas valve is not functioning correctly, which prevents it from regulating the gas supply to the burner.

The boiler's flame detector is sensing a flame incorrectly, even when there shouldn't be one, or it cannot confirm a flame is present when it should be. This is a safety fault.

The boiler failed to ignite successfully during its start-up sequence. This means it couldn't establish a flame to begin heating.

The boiler has failed to ignite after multiple attempts during startup. The display will show 'F.28' and a flame symbol with a cross through it. This indicates a problem with the gas supply or ignition components.

The boiler's flame extinguished during operation, and it failed to re-ignite. This results in the boiler shutting down for safety.

The boiler has detected a fault with its internal fan. The fan is crucial for safely expelling combustion gases and drawing in fresh air.

The boiler has detected an issue with the fan speed, indicating a flue problem. The display will show 'F.32' along with fan symbols. This can be due to a blocked fan or faulty connection.

A fault has occurred in the eBUS communication system, which connects the boiler to external controls and accessories. This can prevent proper communication.

There is a defect in the control of the gas valve. This could be due to a short circuit or earth (ground) leak in the wiring to the gas valves, a faulty gas valve assembly, or an issue with the electronic control system.

The gas valve is not shutting off properly or with a delay. This can indicate a leak in the gas valve or a defect in the boiler's electronics, which is a critical safety concern.

An error has occurred with the boiler's EEPROM (Electrically Erasable Programmable Read-Only Memory). This typically indicates a defect within the boiler's main electronics.

A fault has been detected in the boiler's electronics or with one of the NTC sensors (flow or return). This could be due to a short circuit in the sensor or a defect in the main electronic control system.

The temperature of the boiler's electronic components has become too high. This could be due to external heat effects or a defect within the electronics itself.

The input signal from the flame detector is outside its normal operating limits (either 0V or 5V). This typically points to a defect within the boiler's electronic control system.

The boiler has detected an unstable flame signal, indicating that the flame is not burning consistently or reliably. This can lead to inefficient operation or safety shutdowns.

The boiler is displaying an 'F.70' error because there is no valid Device Specific Number (DSN) set in the display or main board. This often occurs when both the display and main board have been replaced simultaneously without adjusting the DSN.

The boiler's flow NTC (Negative Temperature Coefficient) sensor is reporting a constant temperature value, meaning it is "stuck" and not registering changes. This indicates a defective sensor.

The boiler has detected an implausibly large temperature difference between the flow and return NTC sensors, suggesting one or both sensors are faulty.

The water pressure sensor is sending a signal that is too low, indicating a problem with the sensor itself or its wiring.

The water pressure sensor is sending a signal that is outside the correct range and too high. This can be due to wiring issues or a faulty sensor.

The boiler has failed to detect a change in water pressure when the pump starts, indicating a circulation problem or a faulty sensor/pump. The boiler may be unable to circulate water effectively.

The overheating protection device on the primary heat exchanger has been activated, indicating an extreme overheating event. This is a critical safety shutdown.

The boiler has detected a fault with either the flue non-return flap or the condensate pump. Both are vital for safe and efficient operation of the flue system.

There is a communication error between the display and the main board of the boiler. This prevents proper operation and display of information.

When the burner starts, the boiler fails to register a sufficient temperature change at either the flow or return temperature sensors. This indicates a problem with water circulation or sensor positioning.

The boiler's flow and return temperature sensors are reporting implausible or inconsistent temperature differences. This could be due to incorrect installation or faulty sensors.

The boiler has detected that the flow and return temperature sensors are incorrectly fitted, possibly to the same pipe or the wrong pipes. This prevents accurate temperature measurement.

There's an interruption with the flow sensor NTC. This could be due to a disconnected plug, a loose connection on the PCB, a break in the cable, or a defective sensor.

There's an interruption with the return sensor NTC. This could be due to a disconnected plug, a loose connection on the PCB, a break in the cable, or a defective sensor.

There's an interruption with the Domestic Hot Water (DHW) outlet sensor, often in conjunction with F.91 faults. This could be due to a defective sensor, cable, or plug connection.

There's an interruption with the cylinder sensor, often in conjunction with F.91 faults. This could be due to a defective sensor, cable, or plug connection.

The flow sensor NTC has a short circuit, possibly in the sensor itself, its cable harness, or a short between the cable and casing.

The Vaillant Ecotec Plus Boilers have detected a short circuit in the return temperature sensor (NTC). This indicates an electrical issue with the sensor or its wiring, preventing accurate temperature readings.

The Vaillant Ecotec Plus Boilers have detected a short circuit in the sensor that monitors the temperature of the outgoing domestic hot water (DHW). This electrical fault often occurs in conjunction with fault F.91.

The Vaillant Ecotec Plus Boilers indicate a short circuit with the cylinder sensor. This can happen in combination products with a warm start sensor or with an actoSTOR module, pointing to an electrical fault with the sensor's circuit.

The Vaillant Ecotec Plus Boilers have shut down as a safety measure because a temperature limit has been exceeded. This can be caused by various electrical or heating system issues that lead to overheating.

The Vaillant Ecotec Plus Boilers have entered a safety mode because they detect low or insufficient water pressure within the system. This is a critical safety measure to prevent damage.

The Vaillant Ecotec Plus Boilers have shut down because the temperature difference between the flow and return sensors is too great. This usually indicates a problem with water circulation within the heating system.

The Vaillant Ecotec Plus Boilers have shut down because they detected a very fast rise in temperature. This is a safety measure, often pointing to issues with water circulation or system pressure.

The boiler has safely shut off due to an interruption in the thermal link stat, located at the top of the main heat exchanger. This can be caused by a break in the cable harness or a blocked flue.

The gas valve stepper motor is not functioning, which prevents the gas valve from operating correctly. This could be due to connection issues or a defective motor or electronics.

The boiler has safely shut off because it detects a flame signal even when the gas valve should be closed. This can be caused by moisture on the electronics, a defective flame monitor, or a leaking gas solenoid valve.

The boiler failed to ignite. This can be due to a lack of gas, low gas pressure, blockages, or issues with the ignition system components like the transformer, cable, or electrode.

The boiler failed to ignite. This could be due to a temporary interruption in the gas supply, flue gas recirculation, a blocked condensate duct, or a defective earthing of the product.

The fan is not operating correctly, possibly due to loose connections, a blocked fan, a defective Hall sensor, or faulty electronics.

The fan frost protection function is active, indicating an air pressure switch fault. This could be due to the pressure monitor not switching, insufficient air supply, or issues with the pressure monitor connections or air/flue pipes.

A fault has been detected in the air/flue gas duct, indicating a restriction or blockage that prevents proper air supply for combustion or discharge of flue gas.

A coding resistance fault has occurred, possibly in combination with F.70 (Invalid DSN). This indicates incorrect coding resistors for gas type or an issue with their connection.

A short circuit or overload has been detected on the eBUS communication system, or two power supplies with different polarities are connected to the eBUS.

The mass flow sensor/Venturi is not connected electrically, or its plug is defective or not plugged in correctly.

The combustion regulation system has detected a fault. This can be caused by low gas flow pressure, using the wrong gas coding resistance, or a defective gas valve or mass flow sensor.

There is not enough gas supply for the boiler to operate, often occurring with F.28/F.29 faults. This can be due to closed gas isolation cocks, low gas pressure, or a defective gas valve.

A fault has been detected with the CO (Carbon Monoxide) sensor. This could be due to a cable harness issue, a defective all-gas sensor, or a fault with the main electronics.

The boiler has safely shut off because the CO (Carbon Monoxide) limit has been exceeded. This indicates a defect in the combustion regulation or a contact fault at the gas valve.

The active comfort protection mode has detected a regulation fault. This can be associated with a highly corroded ignition electrode.

The boiler's gas valve is unable to open. This can be due to wiring issues, a faulty gas valve, or a problem with the main circuit board. On older systems (MK1), a high resistance thermal fuse can also cause this.

The boiler detected a delay in the gas valve shutting off after the flame should have extinguished. This indicates the flame signal remained present for too long.

An internal error has occurred with the boiler's electronics, specifically the EEPROM memory. This often points to a problem with the main circuit board.

The flow or return NTC temperature sensor has a short circuit, or there's a general electronics issue.

The boiler's electronic components are overheating, possibly due to external factors or an internal defect.

The boiler's electronics are receiving an unreliable or illogical signal from the flame sensor. This can indicate issues with the ignition electrode or earthing.

This fault occurs if the display board and main PCB were replaced at the same time and the Device Specific Number (DSN) was not reset or is incorrect. It relates to incorrect or missing output range coding resistance.

The flow temperature sensor is signaling a constant value, which is usually incorrect and indicates a problem with the sensor or its positioning.

The temperature difference between the flow and return NTC sensors is too high, indicating a problem with one or both sensors.

The water pressure sensor is reporting a value that is too low, or there is an interruption or short circuit in the sensor or its supply line.

The water pressure sensor is reporting a value that is too high, or its supply line has a short circuit to 5V/24V, or there's an internal fault in the sensor.

This fault indicates issues with the pump, a water shortage, or a defective water pressure sensor. It can also be caused by air in the heating system or blockages.

The safety cut-out (thermal link) in the primary heat exchanger is defective, meaning its feedback doesn't match the gas valve feedback.

The boiler is not receiving a response from the condensate pump. This can mean the pump is defective, or there's an issue with the PCB if no external pump is present.

The DHW (Domestic Hot Water) outlet sensor on an external controller UK link box is connected, but the hot water NTC is not bridged, indicating a compatibility issue with accessories.

The boiler is faulting and showing F80 and F91, indicating a problem with the actoSTOR (shift load pump) inlet sensor or its associated wiring. This is often linked to the cylinder not charging.

The boiler is faulting and showing both F81 and F91, indicating that the cylinder or storage tank is not fully charging within the expected time. This could be due to air in the pump, a defective pump, or blockages.

This fault indicates that the external current anode is either not connected, or its power supply has been interrupted. This is relevant if an external current anode is installed.

When the burner starts, the flow and/or return temperature sensors register little to no temperature change, suggesting insufficient water flow or sensor placement issues.

The flow and return temperature sensors are returning illogical values, possibly due to being inverted or incorrectly installed.

The flow and/or return temperature sensors have been installed on the same pipe or an incorrect pipe.

The underfloor heating contact is open, or the associated sensor is disconnected or defective.

The boiler's electrodes are either not connected, connected incorrectly, or there is a short circuit in their cable harness.

The gas valve is either not connected, connected incorrectly, or there is a short circuit in its cable harness.

The boiler's pump is either not connected, connected incorrectly, or the wrong type of pump is installed. A short circuit in the cable harness is also a possible cause.

The Vaillant Ecotec Plus Boilers are reporting a communication error, specifically with the actoSTOR module. This means the boiler cannot properly exchange information with the module, potentially affecting hot water storage functions.

This fault indicates a problem with a sensor or an actuator component within the actoSTOR module itself. It suggests an internal issue with the module's hardware, affecting its ability to function correctly.

The Vaillant Ecotec Plus Boilers have detected that the coding resistance on its main circuit board (PCB) does not match the configured gas group. This is crucial for proper and safe operation with the correct gas type.

The Vaillant Ecotec Plus Boilers' combustion regulation system has identified that the quality of combustion is not optimal. This can affect the boiler's efficiency, emissions, and overall safety.

A specific fault symbol appears in the bottom left corner of the boiler's display. This indicates that the boiler is in a general error condition and cannot start any test programs.

The boiler may experience ignition problems if the liquid gas tank was not properly purged during the system installation. This prevents the boiler from starting correctly.

The status LED on the actoSTOR module is flashing, indicating a problem with communication. This means the module is not properly exchanging data with the Vaillant Ecotec Plus Boilers.

The status LED on the actoSTOR module is off, which means the module is not receiving any power. Without power, it cannot function or communicate with the Vaillant Ecotec Plus Boilers.

The status LED on the actoSTOR module is solid, indicating that communication is working correctly. This is the normal operating state for the module's communication with the Vaillant Ecotec Plus Boilers.

The display is unable to communicate with the main Printed Circuit Board (PCB) in the electronics box. This means the boiler cannot receive or send control signals or display information correctly.

The boiler is not starting up or providing heat, and no specific fault code is displayed. This indicates a general operational issue that requires basic checks before consulting specific fault codes.

The open-end spanner maintenance symbol on the display indicates that a service interval has elapsed. The boiler is not in fault mode and will continue to operate, but it is recommended to check for more information.

The room thermostat is preventing the boiler from entering heating mode. This could be due to the thermostat being set too low or scheduled off.

The central heating thermostat knob on the boiler is turned off, or the eBUS control unit is not sending a demand for heat. This prevents the boiler from starting the heating cycle.

The boiler's antifreeze protection is active, and there's an unusual variation in the fan speed. The appliance is in a waiting period, blocking normal operation.

The boiler is not receiving a signal for heating from your low voltage external control system. This means the connection at terminals 7-8-9 is not active.

The heating system's water pressure is detected as being too high, exceeding 2.9 bar. High pressure can indicate an issue and may cause the boiler to block operation.

An accessory module or a faulty condensate pump is preventing the boiler's burner from operating. This indicates a problem with an external component connected to the boiler.

The boiler has detected a water shortage condition, specifically a large temperature difference between the flow (VL) and return (RL) pipes. This has activated a waiting period, blocking the boiler's operation.

The boiler has detected a water shortage, indicated by a rapid temperature rise (temperature gradient). This has activated a waiting period, blocking the boiler's operation.

The display shows that the system pressure is too low, indicating that water needs to be added to the boiler. The boiler may not operate until the pressure is corrected.

The boiler is currently performing a check of the return temperature sensor. During this process, any demand for domestic hot water (DHW) or heating is temporarily blocked. This is usually a temporary status.

The boiler is performing a check of both the flow and return temperature sensors. During this process, any demand for domestic hot water (DHW) or heating is temporarily blocked. This is usually a temporary status.

Detecting a smell of exhaust fumes indicates a potential flue gas leak, which carries a risk of poisoning. This can be caused by installation errors, damage, or unauthorized installation sites.

If you detect a smell of gas in the building, this indicates a potential gas leak, carrying a risk of poisoning and explosion. This can be caused by installation errors, damage, or tampering.

The boiler may shut down or operate with unusual ignition and combustion noise if the incorrect type of gas is being used. This can prevent proper and safe operation of the appliance.