BoilerFaultCodesThe 6 most common faults
Your boiler has too much water in the system, causing it to shut down to prevent damage from excessive pressure.
Why it happens: This fault occurs when the water pressure inside your heating system exceeds the safe operating limit. The most common reason is that the filling loop was left slightly open after topping up the system, or the internal expansion vessel has lost its air charge and can no longer balance the pressure changes as the water heats up. In some cases, a leaking internal component might be allowing fresh mains water to constantly enter the system.
Check that the filling loop valves are fully closedBleed water from a radiator using a bleed key to reduce pressureMonitor the pressure gauge to ensure it returns to between 1.0 and 1.5 barReset the boiler once the pressure is stabilised
Your boiler has detected that water is not moving through the system correctly, causing a temperature imbalance that has shut the unit down for safety.
Why it happens: This fault occurs when the boiler's internal sensors detect that water is heating up too quickly or not flowing away from the heat exchanger fast enough. The most common reasons are a failed or blocked circulation pump, air trapped in the system, or a buildup of sludge and debris that has restricted the internal pipework. Because the heat cannot be moved into your radiators effectively, the boiler shuts down to prevent the unit from overheating.
Check that your boiler pressure is between 1.0 and 1.5 bar on the gauge.Ensure all radiator valves and isolation valves under the boiler are fully open.Gently bleed your radiators to remove any trapped air pockets.Reset the boiler by pressing the 'R' or Reset button.
Your boiler has detected an issue with the stability of the electrical power supply coming into your home.
Why it happens: This fault occurs when the boiler's internal computer detects that the incoming electrical supply is not staying at a steady frequency. The most common reason is an unstable local power grid or interference from other high-powered appliances in your home that are distorting the electrical signal. If the power supply is consistent, it usually indicates that the boiler's main control board has become oversensitive or damaged and can no longer process the electricity correctly.
Turn the boiler off using the power button or at the fused spur switchWait for 60 secondsTurn the power back on and check if the code clears as the local grid stabilizes
Your boiler has lost its connection to your room thermostat, meaning it cannot receive instructions on when to turn the heating on.
Why it happens: This fault occurs when the boiler's control board can no longer 'talk' to your room thermostat, usually due to a dropped signal or a hardware failure. The most common reason is simply that the thermostat batteries have run out, but it can also be caused by a faulty wireless receiver or loose wiring between the boiler and its controls.
Check if your wireless thermostat needs new batteries.Ensure the thermostat is within range of the boiler and there are no new obstructions.Check that the thermostat's receiver unit is powered on and plugged in correctly.
Your boiler is struggling to ignite the gas properly and has locked itself out for safety after several failed attempts.
Why it happens: This fault occurs when the boiler's control system attempts to light the gas multiple times but fails to detect a sustained flame. The most common reasons are a faulty gas valve that isn't releasing fuel correctly, or a worn ignition electrode that is unable to produce the spark needed to start the combustion process.
Check that your gas emergency control valve is open and you have credit on your gas meterPress and hold the 'R' or 'Reset' button on the boiler control panel for 3 secondsWait for the boiler to complete its restart sequence to see if the flame generates
Your boiler has detected an issue with its internal combustion levels and cannot regulate the gas flame safely.
Why it happens: This fault occurs when the boiler's internal sensors detect that the gas and air mixture is no longer burning within safe, controlled limits. It usually happens because the gas valve is failing to regulate the flow correctly or the main control board has lost the ability to calibrate the flame, leading the system to shut down for safety.
Press the reset button once to see if the error clearsCheck that your gas supply is active and other gas appliances are workingIf the fault persists after one reset, turn off the boiler and call a Gas Safe engineer
on the Warmhaus Enerwa
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 Warmhaus 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
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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