Error 200

Safety precautions:

- If you smell gas, evacuate the property immediately, call the gas emergency number and do not operate switches or the boiler.

- Switch off electrical power to the boiler at the isolator before opening any panels.

- Take care with hot surfaces and hot water — risk of scalding.

- Do not attempt internal repairs, remove covers beyond user-accessible panels, or work on gas or sealed parts unless you are Gas Safe registered.

Initial checks a homeowner can do:

1. Confirm what 200 means on the display: it shows the boiler is in heating mode (central heating demand). Check whether your heating schedule or thermostat is actually set to call for heat.

2. Check the programmer/timer: ensure the CH (central heating) program is set correctly and hasn’t been left on or overridden. Cancel any temporary boost or manual override.

3. Check the room thermostat: raise the set temperature to see if the boiler responds, and check batteries if the thermostat is battery powered. For wireless thermostats, ensure they’re within range and powered.

4. Check TRVs: Make sure individual radiator thermostatic valves are not jammed wide open or fully closed unintentionally.

5. Check boiler pressure: look at the pressure gauge on the boiler. Normal system pressure is typically around 1.0–1.5 bar when cold. If pressure is very low (below ~0.8–1.0 bar) the boiler may not operate correctly.

Specific diagnostic and simple fix steps:

1. If the boiler is running and radiators are warm and this is expected, no action is needed — 200 is normal operation.

2. If the boiler is in heating mode but you do not want heat: cancel any CH demand on the programmer and turn down the room thermostat. If a smart thermostat is in use, check its schedule and app settings and temporarily set it to ‘off’ or ‘heat off’ to test.

3. If the boiler shows 200 but will not fire (no flame or no heat): check the programmer and thermostat are calling for heat, then check pressure. If pressure is low and you are comfortable doing so, you can re-pressurise the system using the filling loop according to your boiler manual. If unsure, call an engineer.

4. For wireless thermostat systems showing additional thermostat error codes (e.g., A21 in other contexts indicates RF/communication loss), check thermostat batteries, re-pair the thermostat to the receiver per the manufacturer instructions, and ensure there is no large metal object or new Wi‑Fi device blocking the signal path.

5. If the boiler displays 200 but also shows other fault codes or symbols (for example EA, E9, CE etc.), do not ignore those. Some EA codes and temperature/pressure faults indicate ignition, condensate, sensor or safety limiter issues — avoid repeatedly resetting the boiler if an EA code appears; follow the manufacturer guidance and call a Gas Safe engineer.

6. If the system pressure is too high or too low, or you see pump or circulation warnings (cold radiators, large temperature differences between flow and return), you may need bleeding of radiators or a professional check of the pump and valves.

When to call a professional:

- Call a Gas Safe registered engineer if you detect gas smell, persistent lockouts, repeated fault codes other than 200, ignition or flame faults, suspected condensate blockage, blocked pump, faulty sensors, overheating or if you are unsure how to safely re-pressurise the system.

- Do not attempt to repair gas valves, burners, fan, PCB, sensors or flue components yourself. Only a qualified engineer should work on these items.

Notes and cautions:

- Error 200 alone is informational — treat it as a state indicator first. If the boiler behaves unexpectedly or other faults appear, stop and seek professional help.

- Avoid repeated resets when the display shows EA codes or other safety-related faults; follow the manual and contact a Gas Safe engineer for those conditions.