BoilerFaultCodesThe 6 most common faults
Your boiler has detected that the water is heating up too quickly or isn't circulating properly through the system.
Why it happens: This fault occurs when heat isn't being moved away from the boiler's internal heat exchanger fast enough, causing a rapid temperature spike. The most common reasons are a failing circulation pump, a blockage in the system pipework, or air trapped within the unit preventing water flow.
Check that the boiler pressure is between 1 and 1.5 bar on the gaugeEnsure all radiator valves are fully openCheck for any visible leaks around the boiler or pipeworkRestart the boiler using the reset button
Your boiler is overheating because water isn't moving through the system quickly enough to be cooled down.
Why it happens: This fault occurs when the water inside your boiler heats up too quickly because it isn't being pumped away and into your radiators fast enough. The most common reasons are a pump that has seized up or a build-up of sludge and debris in the system that is restricting the flow of water.
Check that your boiler pressure is between 1 and 1.5 bar on the gaugeEnsure all radiator valves are fully openRestart the boiler using the reset button
Your boiler has detected that it is getting too hot too quickly, usually because water isn't moving through the system properly.
Why it happens: This fault occurs when the water inside the boiler heats up much faster than the system can carry it away, causing it to reach a dangerous temperature in seconds. This is usually caused by a pump failure, a blockage in the pipes, or trapped air, all of which prevent the water from circulating properly. Essentially, the boiler is producing heat but has nowhere to send it, so it shuts down to prevent internal damage.
Check that your boiler pressure is between 1 and 1.5 bar on the gauge.Ensure all radiator valves are fully open to allow water to flow.Restart the boiler to see if the temporary fault clears.
Your boiler has stopped working because water is not moving through the system properly or a temperature sensor has detected an overheating issue.
Why it happens: This fault occurs when the boiler's internal sensors detect that heat is not being carried away from the burner quickly enough, leading to an overheat risk. The most common reasons are a failed pump that isn't pushing water around, or a blockage caused by sludge and debris inside the pipework or heat exchanger. In some cases, it may simply be caused by a faulty sensor sending an incorrect temperature reading to the main control board.
Check that your boiler pressure is between 1.0 and 1.5 bar on the internal gauge.Ensure all radiator valves and any isolation valves under the boiler are fully open.Attempt to reset the boiler by turning the selector switch to the reset position for five seconds.Bleed your radiators to remove any trapped air that may be blocking circulation.
Your boiler is temporarily confused by its internal software settings and cannot start up correctly.
Why it happens: This fault occurs when the boiler's internal computer becomes confused about which specific model it is supposed to be. It is usually caused by a glitch in the software or a communication error between the electronic components after a power surge or a component failure. Because the boiler cannot confirm its own identity and safety parameters, it shuts down as a protective measure.
Locate the selector switch or reset button on the front of the boiler.Turn the switch to the 'R' (Reset) position and hold for at least 5 seconds.Wait for the boiler to restart; if the code repeats, a Gas Safe engineer must reconfigure the internal board.
Your boiler's computer brain is momentarily confused by some internal settings and cannot operate correctly.
Why it happens: This fault occurs when the boiler's main control board loses its specific configuration settings or detects a mismatch in its internal programming memory. It is often triggered by a sudden electrical surge, a failing memory chip, or a breakdown in the communication between the boiler's internal components. Because the boiler no longer knows its own operating limits or model type, it shuts down as a safety precaution.
Locate the selector knob on the front of the boiler control panel.Turn the knob to the 'Reset' position and hold it for five seconds.Return the knob to your desired setting and wait for the boiler to restart.
on the Baxi 200 Combi (range)
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Baxi shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue