Error 612

Safety precautions:

- If you smell gas, leave the property immediately and call the gas emergency number. Do not attempt any checks.

- Before opening or working on the boiler isolate the electrical supply at the fused spur and, if you must, isolate the gas supply. Only qualified personnel should remove the boiler casing or work on internal components.

- Never try to bypass safety devices or run the boiler with the fan disconnected or immobilised.

Initial homeowner checks you can safely do:

1) Note the exact error (612) and any other codes or spanner/service symbols on the display.

2) Try a single reset using the boiler’s reset button or following the user manual. If the fault clears and does not return after normal operation, monitor the boiler closely. If it reappears, stop further DIY attempts.

3) Check the boiler’s fused spur or external plug fuse (some ATAG units have a 3 A fuse in the plug or fused spur). Replace a clearly blown external fuse with the correct rating if you are comfortable doing so.

4) Confirm general mains power: check the consumer unit (tripped breaker) and that other appliances are powered.

5) Inspect the external flue terminal and air intake for obvious blockages (bird’s nest, leaves, snow/ice). Clear only external obstructions; do not force objects into the flue.

6) Make sure vents and air pathways in the room where the boiler sits are not blocked.

If the basic checks above do not fix it, call a qualified engineer. The following steps are diagnostic and repair tasks for a Gas Safe registered engineer:

1) Isolate electrical supply and gas before removing the casing.

2) Remove the boiler cover and visually inspect the fan assembly for seized impeller, debris, foreign objects, or mechanical damage. Check the fan gasket and non-return valve area for correct fit and signs of wear.

3) Check all fan connectors and wiring for loose pins, corrosion, or damage. Re-seat connectors and secure wiring.

4) Check any accessible fuses on the PCB and the boiler’s internal wiring for signs of shorting or damage.

5) With the boiler powered and calling for fan (engineer procedure), measure that the PCB is supplying the correct voltage to the fan motor. If voltage is present but the fan does not spin, the fan motor is faulty and should be replaced.

6) If no supply voltage is present to the fan when it should be running, diagnose the control board outputs, relays or speed-control circuitry. Replace or repair the PCB if it fails to command the fan.

7) Test the fan motor windings for correct continuity and test any start/run capacitor if fitted. Replace the capacitor if out of specification.

8) If replacing the fan, fit the correct replacement assembly and any seals/gaskets supplied by the manufacturer. Reassemble with correct gas washer/seal and ensure the flue joint is gas-tight.

9) After repair, restore power and gas, perform the manufacturer’s commissioning and safety checks including combustion/CO check and ensure the fan speed control and flue evacuation are correct. Run the boiler through a full heating cycle and confirm the 612 fault does not return.

When to call a professional:

- If the fault persists after a reset and the simple external checks above.

- If any internal inspection, electrical testing, fan removal or replacement is required.

- If you are not competent with electrical testing or gas-safe procedures.

A Gas Safe registered engineer must carry out internal repairs and final safety and combustion checks. Do not attempt to run the boiler with the fan disabled or to bypass safety interlocks.