Error C1 264

Safety precautions:

- If you smell gas or suspect carbon monoxide (symptoms include headache, dizziness, nausea, flu-like symptoms), turn off the gas supply at the meter if safe to do so, switch the boiler off at the mains, ventilate the area, leave the property and call the gas emergency number and a Gas Safe engineer immediately. Do not stay in the property.

- Always isolate electrical power to the boiler before opening or attempting any inspection inside the casing. If you are not competent with electrical systems, do not open the boiler.

- Never attempt to repair gas components unless you are a Gas Safe registered engineer.

Initial checks a homeowner can do (safe, no internal access required):

1. Note and record the fault code (C1 264), the boiler model and serial, and the exact behaviour (e.g. boiler displays C1 264 and locks out). Take a photo of the display for the engineer.

2. Try a simple reset: turn the boiler off via the programmer or isolator, wait 1–2 minutes, then turn it back on and press the boiler reset button once as per the manual. If the fault clears and stays cleared, monitor the boiler — if it reoccurs, book an engineer.

3. Check mains power and the boiler isolator: verify other electrical items work, check the fused spur or switch that feeds the boiler hasn’t been turned off or tripped. Do not remove covers or touch wiring.

4. Inspect visible air intake vents and the flue terminal outside for obvious blockages (bird nest, leaves, debris, snow, paint, or building materials). Clear safely if external and accessible without climbing or removing guard covers.

5. Check the area around the boiler: remove dust, debris, or items blocking the appliance ventilation. Ensure adequate clearance and ventilation as per the boiler manual.

6. In cold weather check for a frozen condensate pipe (common on some faults) that can affect operation; if you suspect freezing, gently thaw with warm (not boiling) water along the external run of the condensate pipe, or call an engineer.

Specific diagnostic pointers (for information to give the engineer; do not open the boiler unless qualified):

1. Listen when the boiler attempts to start: you should normally hear the fan run for a few seconds as the boiler goes into pre-purge. If you hear no fan noise at all, the fan may not be receiving power or the motor may have failed.

2. If the fan spins but the fault persists, the air pressure switch or its tube/hoses may be blocked, damaged or not switching correctly, or the PCB input that reads the pressure switch may be faulty.

3. If power to the fan appears intermittent, the issue could be wiring, connectors, a blown internal fuse, or a failing PCB output stage.

4. If you can safely provide these details to the engineer it will speed diagnosis: whether the fan is audible, whether the fault appears straight away or after some running, any previous intermittent issues, and any recent work or vents blocked near the boiler.

When to call a professional and what to expect:

- If the reset does not clear the fault, if you hear no fan during start-up, or if you find blocked flue/airway you cannot clear safely, switch the boiler off and call a Gas Safe registered engineer. Any internal inspection, electrical testing, fan replacement, air pressure switch cleaning/replacement, wiring repairs, or PCB work must be carried out by a qualified engineer.

- Provide the engineer with the error code, times of occurrence, photos, and what checks you’ve already done. The engineer will test the fan, the air pressure switch and its tubing, the fan wiring and connector, and the PCB outputs; they will then decide whether a repair or part replacement is required.

Prevention and notes:

- Regular annual servicing by a Gas Safe engineer reduces the chance of fan and pressure-switch faults. Keep external flue terminals and air intake vents clear of debris, bird nests and leaves. Keep the boiler area clean and free from dust and obstructions.

- Do not attempt internal electrical or gas repairs yourself. If the boiler locks out repeatedly with this fault, discontinue use until a Gas Safe engineer has inspected it.