Johnson Starley Aquair S 10 Fault codes & diagnostics

3 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Heat Interface Unit Natural Gas 10 kW Discontinued

Download the Johnson Starley Aquair S 10 manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Just want the most common Johnson Starley Aquair S 10 faults?

The top 6 problems in plain English — with causes, DIY checks and repair costs.

Fault codes

All 3 documented codes

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Parts commonly replaced

Fan assembly
Control PCB

Parts commonly replaced

Printed Circuit Board (PCB)
Wiring Harness

Parts commonly replaced

Temperature sensor
Wiring harness

Status & diagnostic codes

90 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

0.45 Diagnostic Your boiler is not operating correctly because it has detected an internal communication failure between its electronic control boards. 0.46 Diagnostic Your boiler has detected a critical internal error that prevents it from starting safely, requiring professional attention. 0.47 Diagnostic Your boiler's internal computer has identified an electrical fault within the control system that is preventing the unit from operating safely. 0.48 Diagnostic Your boiler has detected an internal communication error between its main control components, causing it to stop operating to protect the system. 0.49 Diagnostic Your boiler has detected a communication error between its internal electronic control systems, preventing it from operating correctly. 0.50 Diagnostic Your boiler is not firing because it cannot detect a flame, likely due to a combustion or ignition failure. 0.51 Diagnostic Your boiler is failing to light the burner because it cannot detect a flame, causing the system to stop working as a safety precaution. 0.53 Diagnostic Your boiler's control system has detected a potential internal hardware failure that is preventing it from operating safely. 0.54 Diagnostic Your boiler has detected a failure in its internal communication system, which has caused it to stop operating to prevent further damage. 0.55 Diagnostic Your boiler's air pressure switch is failing to detect the correct airflow, which stops the system from starting to keep your home safe. 0.56 Diagnostic Your boiler has detected a communication error with its control system, which means it cannot operate correctly and has automatically shut down to stay safe. 0.58 Diagnostic Your boiler is failing to light the burner because it cannot detect a flame, meaning your system will not provide any heating or hot water. 0.59 Diagnostic Your boiler's internal computer is having trouble processing information and needs to be reset to try and clear the error. 0.60 Diagnostic Your boiler has detected an issue with its internal heat sensor, which is preventing the unit from safely regulating its temperature. 0.63 Diagnostic Your boiler has detected an issue with the internal communication system, preventing it from operating correctly. 0.65 Diagnostic Your boiler has detected an issue with its internal communication or electronic control system which is preventing it from operating correctly. 0.66 Diagnostic Your boiler's electronic control system is failing to communicate correctly, which has caused the unit to shut down for safety reasons. 0.68 Diagnostic Your boiler has detected an internal fault relating to the main electronic control system, meaning it cannot operate safely and has shut itself down. 0.70 Diagnostic Your unit has detected an issue with its internal heat sensor, which is preventing it from safely regulating the temperature of the air it distributes. 0.71 Diagnostic The unit has detected an issue with its internal air temperature sensor or communication, causing it to stop operating correctly. 0.73 Diagnostic Your boiler is failing to light the burner because it cannot detect a flame, causing the system to stop working as a safety precaution. 0.75 Diagnostic Your boiler has detected an issue with the water pressure or circulation flow that is preventing it from starting up correctly. 0.76 Diagnostic Your boiler is failing to light the burner because it cannot detect a flame, causing it to lock out for safety. 0.78 Diagnostic Your boiler has detected an issue with its internal communication or electronic control system that prevents it from operating correctly. 0.80 Diagnostic Your boiler has detected that the water temperature has risen too high and it has automatically shut down to prevent damage. 0.82 Diagnostic Your unit has detected a specific internal data error indicating a malfunction within the main control system's communication. 0.84 Diagnostic Your boiler has detected an internal sensor communication error that is preventing it from operating correctly. 0.86 Diagnostic Your boiler has detected a communication error with its internal temperature sensor, causing it to shut down to prevent incorrect heating operation. 0.88 Diagnostic Your heating unit is indicating a system lockout or sensor error that prevents the boiler from firing up. 0.90 Diagnostic Your heating system has detected an issue with the heat output sensor or internal temperature readings, causing the unit to stop heating your home as a precaution. 0.92 Diagnostic Your boiler has detected an issue with the internal communication or sensor data flow, meaning it cannot safely regulate its heating functions. 0.95 Diagnostic Your boiler has detected an internal communication error and has safely shut itself down to prevent further system problems. 0.97 Diagnostic Your boiler has detected an issue with the internal communication system, preventing it from operating correctly. 0.99 Diagnostic Your boiler has detected a communication error between its internal electronic control systems, preventing it from operating correctly. 1.02 Diagnostic Your boiler is not firing because it has failed to detect a flame during the ignition process. 1.04 Diagnostic Your boiler is failing to ignite because it has detected an issue with the flame sensing or fuel supply, preventing it from starting up safely. 1.07 Diagnostic Your boiler has detected an issue with the heat exchanger's temperature, causing it to lock out for safety to prevent overheating. 1.09 Diagnostic Your boiler is failing to light the burner because it cannot detect a flame, causing the unit to shut down for safety reasons. 1.12 Diagnostic Your boiler is failing to light the burner due to an internal issue with the ignition process. 1.15 Diagnostic Your boiler has detected an internal communication error and has safely shut down to prevent further faults. 1.17 Diagnostic Your boiler is not detecting that the burner has successfully lit, so it has shut down as a safety precaution. 1.20 Diagnostic Your boiler has detected a failure to ignite the burner, meaning it cannot produce heat or hot water. 1.23 Diagnostic Your boiler has detected an issue with its internal air supply or exhaust ventilation, which prevents it from igniting safely. 1.26 Diagnostic Your boiler has detected a communication error between its main control unit and the internal sensors, causing it to stop operating as a safety precaution. 1.29 Diagnostic Your boiler has detected an internal communication error and has safely shut down to prevent further issues. 1.32 Diagnostic Your boiler has detected an issue with the air pressure or flue system, meaning it cannot safely vent exhaust gases, so it has shut down to protect your home. 1.35 Diagnostic Your boiler has failed to ignite because it cannot detect a flame, likely due to a sensor issue or a problem with the gas supply. 1.39 Diagnostic Your unit has detected an issue with the air flow or pressure levels, causing the system to automatically shut down as a safety precaution. 1.42 Diagnostic Your boiler has detected a communication error or internal electronic fault that is preventing it from starting up correctly. 1.45 Diagnostic Your boiler has detected a communication error between its internal electronic control systems and has shut down for safety. 1.49 Diagnostic Your boiler is failing to detect the water flow correctly, meaning it has safely switched itself off to prevent overheating. 1.52 Diagnostic Your boiler has detected a communication issue between its internal electronic control systems and has shut down to prevent incorrect operation. 1.56 Diagnostic Your boiler is failing to light the burner because it cannot detect a flame, causing it to shut down for safety reasons. 1.59 Diagnostic Your boiler has detected an internal issue with the water heating process and has safely shut itself down to prevent damage. 1.63 Diagnostic Your boiler is failing to ignite the burner, meaning it cannot produce any heat or hot water. 1.67 Diagnostic Your boiler is not firing because it cannot detect that the fan is spinning correctly to clear waste gases. 1.71 Diagnostic Your boiler's control system has detected an internal communication error, which has caused it to stop operating to prevent further damage. 1.75 Diagnostic Your boiler has detected an internal communication error between its internal components, preventing it from operating safely. 1.79 Diagnostic Your boiler's electronic control system is reporting a internal communication error, meaning it cannot correctly process operational commands. 1.83 Diagnostic Your boiler has detected a communication error between its main control board and the internal sensors, causing it to stop operating as a safety precaution. 1.87 Diagnostic Your boiler's control system has encountered a communication error with its internal memory, preventing the unit from starting your heating. 1.91 Diagnostic Your heating system has encountered a communication error between the main controller and the fan, meaning the unit is unable to start up properly. 1.95 Diagnostic Your boiler has detected an issue with the heat exchanger or its temperature sensors, meaning it has safely shut down to prevent overheating. 1.99 Diagnostic Your boiler's internal computer has lost communication with the main control board, preventing it from functioning correctly. 2.04 Diagnostic Your boiler is not firing because it has detected a problem with the fan system that pushes waste gases safely out of your home. 2.08 Diagnostic Your boiler's internal computer has identified a significant fault within the control system that is preventing the unit from operating safely. 2.13 Diagnostic Your boiler has detected an issue with its internal air pressure or venting system, which is preventing it from safely starting up. 2.17 Diagnostic Your heating unit is experiencing a communication fault between the internal control system and the boiler, which has caused the unit to stop operating to ensure safety. 2.22 Diagnostic Your boiler has detected an issue with the electrical communication between its main computer and the internal sensors, causing it to stop operating to remain safe. 2.26 Diagnostic Your boiler has detected a failure in the system's ignition process and has safely shut itself down to prevent any unsafe gas buildup. 2.31 Diagnostic Your boiler has detected an issue with the air pressure or airflow within the system, meaning it has safely shut itself down to prevent unsafe operation. 2.36 Diagnostic Your boiler is not firing because it has detected an issue with the ignition process or the flame safety system. 2.40 Diagnostic Your boiler has detected an issue with the heat exchanger's temperature, causing the system to stop working to prevent overheating. 2.45 Diagnostic Your boiler has detected an issue with its internal air pressure sensing system, which prevents it from igniting safely. 2.50 Diagnostic Your boiler is not operating correctly because it has identified an internal system fault that requires professional intervention to resolve. 2.55 Diagnostic Your boiler has detected an issue with the internal water pressure, which is preventing it from heating your home safely. 2.60 Diagnostic Your boiler has detected an issue with its internal heat sensor, which is preventing it from safely regulating the water temperature. 2.65 Diagnostic Your boiler has detected an internal communication or software issue that is preventing it from operating correctly. 2.70 Diagnostic Your boiler has detected an internal communication error between its main control components, causing it to shut down for safety. 2.75 Diagnostic Your boiler has detected an issue with the airflow or combustion system, meaning it cannot operate safely and has shut down to protect your home. 2.79 Diagnostic Your boiler's internal computer has identified an unexpected electrical or communication fault that is preventing the system from operating correctly. 2.84 Diagnostic Your boiler has detected an issue with the air pressure or airflow within the system, preventing it from operating safely. 2.89 Diagnostic Your boiler has detected an internal communication failure between the control panel and the main heating system, causing the unit to stop operating safely. 2.94 Diagnostic Your boiler has detected a failure in the internal electronic control system that prevents it from starting up safely. 2.99 Diagnostic Your boiler has detected a critical internal error that prevents it from starting safely. 3.04 Diagnostic Your boiler has detected an issue with the heat exchanger's temperature monitoring, which has caused it to stop working to prevent internal damage. 3.09 Diagnostic Your boiler is failing to light the burner because it cannot detect a flame, causing the system to stop working to keep you safe. 3.14 Diagnostic Your boiler has detected a failure in its internal communication system, meaning it cannot properly coordinate its heating functions. 3.19 Diagnostic Your boiler's control system has detected a fault with the primary circuit board, causing the unit to stop operating safely. 3.24 Diagnostic Your boiler has detected a communication error between the main controls and the heating system, meaning it cannot properly manage your home's temperature.