Error 201

Safety precautions:

- If you smell gas, evacuate the property immediately, do not operate electrical switches, and call your gas emergency number and the Gas Safe authority. Do not attempt internal repairs.

- Do not remove the boiler cover, work on the gas supply, or replace internal components unless you are a Gas Safe registered engineer. Electricity to the boiler can be isolated for safe checks, but avoid internal electrical work.

- Have the boiler manual, model number, and any displayed fault codes ready for an engineer.

Initial checks a homeowner can do:

1) Confirm demand: open a hot tap and watch the boiler display. If 201 appears while the tap is open and the boiler fires and supplies hot water, the code is just showing normal DHW mode.

2) Check programmer/timer and any hot-water thermostats or smart controls to ensure hot water has not been scheduled or locked on by accident.

3) Check system water pressure on the boiler gauge; it should typically be around 1.0–1.5 bar when cold. If pressure is low (well below 1.0 bar) top up the system using the filling loop per your manual.

4) Observe whether heating behaves normally. If central heating works but there is no hot water, that points toward the diverter valve or a hot-water sensor issue.

5) Note any other error codes or unusual noises (fan not running, loud banging, or long ignition attempts). Record what you see for the engineer.

Specific diagnostic and basic fix steps you can safely try:

1) Run a hot tap and watch: if the boiler fires and hot water follows, no action required. If you have hot water intermittently, try bleeding a radiator to check flow is not impeded and re-check pressure.

2) Cancel any hot-water demand from the programmer or thermostat to see if the display returns to standby. If the boiler stays in DHW mode with no demand, proceed to step 3.

3) Reset the boiler once using the manufacturer reset procedure (press the reset button once or follow the manual). Wait for the boiler to complete its restart cycle. Do not repeatedly reset; if the fault returns immediately, stop and call a professional.

4) If pressure is low, repressurise to the recommended value (usually 1.0–1.5 bar) following the instructions in your manual, then re-check operation. Low pressure can prevent normal DHW operation.

5) Check for visible leaks around pipes, cylinders, radiators and the boiler. Fixing a leak or repressurising can resolve related faults.

6) If the boiler will not fire for DHW but will for heating (or vice versa), suspect the diverter valve or its actuator. This is not a DIY repair for most homeowners; arrange an engineer to test and, if necessary, replace the diverter valve/actuator.

7) If you notice the fan is silent at startup and the boiler shows fail-to-start symptoms, or you see other appliance fault codes (EA, CE, etc.), do not attempt internal fixes — this may indicate fan, control board or safety sensor faults and requires a qualified engineer.

When to call a professional:

- If resetting the boiler does not clear the issue or the code returns.

- If you have no hot water despite the boiler showing DHW mode, or the boiler is locked in DHW mode when no demand exists.

- If you find leaks, loss of pressure you cannot fix, repeated fault codes, or suspect a failed diverter valve, sensor, pump, fan or PCB.

- If there is any smell of gas, visible water leaks from the boiler, or loss of flame/ignition faults.

Important notes:

- Do not attempt to replace the diverter valve, gas valve, sensors, or open the sealed boiler compartment unless you are Gas Safe registered.

- Provide the engineer with the exact model (GB162), the 201 indication, any other codes shown, and what checks you’ve already performed to speed diagnosis.

- Regular servicing by a Gas Safe registered engineer reduces the chance of faults. If in doubt or if the problem persists, arrange a Gas Safe service visit.