Error Fast flash

Safety precautions:

1) If you are not competent with electrical work or gas appliances, stop and call a Gas Safe engineer. Working on boilers can be dangerous. 2) Isolate mains electricity to the boiler before removing covers. 3) If any gas-side components are disturbed (gas valve, manifold, burner), the appliance must be tested and relit by a Gas Safe engineer. 4) Use appropriate PPE (insulated multimeter probes, eye protection) and follow manufacturer guidance.

Initial homeowner checks (safe, simple):

1) Press and hold the reset button (usually the lower button) for about 3 seconds. Observe the blue light: if the blue light becomes steady for a few seconds then fast-flashes again, that behaviour points toward the fan circuit. If the fault clears and stays green, monitor for recurrence and book a service. 2) Check the boiler display information/cause code: press the spanner/return to view the cause code shown alongside the fault; note any alphanumeric cause (e.g. C6/C7/B1/E2) to tell an engineer. 3) Check the boiler’s external vent and flue for obvious blockages or debris. 4) Verify mains power to the boiler and that the external isolator is on. 5) Check visible wiring and connectors for obvious damage, corrosion or loose plugs, especially at the fan and sensor connectors.

Diagnostic steps (for a competent person only):

1) Reproduce the fault: with a demand active, turn on the boiler and observe the fast-flash behaviour. 2) Use the cause code from the info menu to prioritise checks (B1/code plug, C6/C7/fan, E2/flow sensor etc.).

3) Fan electrical check: with the front cover removed and keeping the appliance powered (only if you are competent), locate the fan connector. Using a multimeter set to AC voltage measure between the brown and purple fan wires when the boiler is trying to start the fan. You should see mains voltage (~230–240VAC) applied. If 240V is present and the fan does not spin, the fan assembly is faulty and needs replacement. If voltage is not present, the problem is in the control electronics, wiring harness or connectors upstream — do not attempt PCB repair; call an engineer.

4) Fan mechanical check: visually inspect the fan for seized bearings, foreign objects or damage. Spin the fan impeller by hand (with power isolated) to check for free rotation. Replace the fan assembly if seized or noisy. If replacing the fan, replace any gaskets/seals supplied and follow the manufacturer reassembly torque/positioning guidance. Remember re-commissioning gas-side work must be done by a Gas Safe engineer.

5) Code plug (identification module/KIM) check: with power isolated, check the code plug/module is seated correctly on the PCB and connectors are clipped in. A B1 or similar cause code indicates the board cannot read the identification module. Reseating can sometimes clear the fault; if the code plug is missing or defective it must be replaced.

6) Sensors and wiring: if the cause code or information menu points to flow/return/safety sensors, inspect connectors for corrosion or moisture, check wiring continuity and that sensor plugs are fully engaged. Sensor faults can cause fast-lockouts on some Greenstar Ri variants. Do not replace sensors unless qualified; incorrect fitting or wiring can create hazardous conditions.

Repair and re-test notes:

1) After any repair or reseating, restore power and attempt a reset. Check the information menu to confirm the cause code clears. 2) If you replaced the fan or any part that required disturbing the gas or burner area, a Gas Safe engineer must carry out leak and safety checks, and fully commission the boiler. 3) If the fault returns or the electrical supply to the fan is absent, do not attempt PCB repairs — call a trained engineer.

When to call a professional:

1) If you cannot clear the fault with the safe checks above, if you are unsure about using an electrical meter on the boiler, or if the diagnosis points to fan replacement, PCB/control box or gas-side disturbance, call a Gas Safe–registered engineer. 2) Any task involving the gas manifold, burner, relighting or safety checks must be carried out by a qualified engineer.

Summary: try the safe initial checks (reset, view cause code, visual inspection). If the fan doesn’t run but has 240V at its connector the fan assembly is almost certainly faulty and will need replacing. If voltage to the fan is missing, or if the code plug or sensors appear at fault, get a Gas Safe engineer to diagnose and repair.