Error A1 281

Safety precautions:

- If you smell gas, leave the property immediately and call your gas emergency number — do not attempt any checks or resets.

- Turn mains electrical power to the boiler off before opening the boiler cover. Do not work inside the boiler if you are not qualified. Avoid touching wiring, gas valves or electronic modules.

- Avoid repeated resets of the boiler if the fault returns immediately — that can mask an ongoing fault and risk damage.

Initial checks a homeowner can do:

1. Check the boiler display and quick-info text (if available) to confirm A1 281 and any additional messages. Note whether the fault is permanent or only appears when calling for heat/hot water.

2. Check system water pressure on the boiler gauge when cold. Normal is around 1.0–1.5 bar for most sealed systems. If pressure is below about 1.0 bar, topping up is required.

3. Inspect visible pipework, radiator valves and the area under the boiler for any obvious leaks. Check the pressure relief valve (PRV) discharge pipe outside/under the boiler for drips or wetness.

4. Bleed one or two radiators (start with those furthest from the boiler) to release trapped air. If radiators sound gurgly or are cold at the top and warm at the bottom, they likely need bleeding.

5. If you have a visible magnetic/system filter installed on the pipework, check for external signs of leakage. Do not remove or clean the internal element unless you are competent and can isolate and drain the system safely.

How to top up system pressure (general guidance):

- Only top up when the boiler is cold. Locate the filling loop or internal filling key for your unit (refer to the boiler handbook or manufacturer videos for your exact model).

- Open the filling loop valves slowly while watching the pressure gauge. Close the valve(s) as soon as pressure reaches about 1.0–1.5 bar (follow the boiler handbook recommendation). Remove or secure the filling loop if it is a removable flexible hose.

- Re-pressurising may clear a pressure-related A1 if the pump was running dry. After topping up, switch the boiler back on and reset the fault (use the spanner/return button or follow the handbook). If the code clears and the system runs normally, monitor pressure over the next days for continuous loss.

If pressure is fine after topping up and the fault remains:

- After turning the boiler off and isolating electrical supply, listen for the pump when the boiler is switched on again: a healthy pump will run quietly; a failed pump may be silent or make grinding/noisy sounds. Do not probe inside the boiler while it is live.

- If you suspect an airlock remains after bleeding, bleed more radiators and re-check pressure. Re-pressurise if pressure drops during bleeding.

- Check for sludge signs: very cold radiators or poor circulation despite the pump running can suggest sludge or blockage. A blocked pump or system will need a professional diagnosis and likely filter cleaning, powerflush or pump removal for inspection.

When to call a professional (and what they will do):

- Call a Gas Safe registered engineer if: pressure repeatedly falls, you find a leak, the pump is noisy/grinding or hot, bleeding and topping up do not clear the fault, or the boiler still shows A1 281 after basic checks and reset. Do not attempt to dismantle the pump or internal boiler components yourself.

- A qualified engineer will safely isolate and inspect the pump, check electrical connections and the PCB code plug, remove and inspect or replace the pump if bearings/shaft are seized, clean or replace the magnetic filter, test for sludge and advise on powerflushing if required, and check the PRV and filling loop. They will also check for any related control or sensor faults.

Notes and cautions:

- Avoid physically forcing the pump shaft or attempting complex repairs inside the boiler yourself — that work requires isolation, draining, and Gas Safe qualifications. Simple actions like bleeding radiators, checking for leaks, topping up the system and resetting the boiler are reasonable for a competent homeowner, but any intervention beyond that should be left to a professional.

- If the boiler repeatedly locks out with A1 281 after your checks, stop attempting resets and book an engineer. Prompt attention prevents further pump damage and restores reliable heating/hot water.