Error T1

Safety precautions:

- If you smell gas, leave the property immediately and call the gas emergency number. Do not touch electrical switches or the boiler. Do not attempt repairs.

- Only perform external, non-invasive checks. Do not open the boiler casing, touch live components, or attempt to replace gas or electrical parts unless you are a qualified Gas Safe engineer.

- Limit boiler resets to one or two attempts. Repeated resetting can mask a developing fault and is unsafe.

Initial homeowner checks you can do:

1. Note exactly how the T1 appears: is it a single brief message during normal start or is it followed by a flashing fault, triangle, or lockout? Record any other codes or lights.

2. Check mains power to the boiler: ensure the isolator switch and any fused spur are on and the house fuse has not tripped.

3. Check gas supply: confirm other gas appliances (hob, oven) are working. If there is no gas to the property contact your gas supplier before calling an engineer.

4. Check system water pressure on the boiler gauge (should be around 1–1.5 bar when cold for a combi). Very low pressure can prevent normal operation.

5. Reset the boiler following the manufacturer instructions (usually press the spanner/return or reset button). Try one reset and observe whether the boiler starts normally or returns to T1/lockout.

6. Check the condensate pipe for blockages or freezing (common in cold weather). A blocked condensate can stop the boiler from completing the start sequence. If frozen, thaw with warm (not boiling) water poured gently; if blocked, clear or call engineer.

Specific diagnostic observations and limited actions:

1. Listen and watch on start: when there is a demand for heat the fan/pump should run briefly then you should hear a clicking spark and gas ignition. If you hear the fan/pump but no spark/click, the ignition electrode or spark generator may be at fault. If you hear spark but no ignition, suspect gas supply or valve.

2. You can visually inspect the external ignition leads and connectors for obvious damage or loose plugs (only with the boiler isolated and cooled down). Do not probe connectors with power applied. Re-seating obvious plug-in connectors can sometimes restore a connection, but do not force or dismantle internal components.

3. If the T1 is accompanied by an EA or no ionisation message, it usually means the flame sensor did not detect a flame after ignition. This may be due to gas supply, dirty electrode, faulty electrode/lead, or a failed control module.

4. If you have already checked for spark (as you said) and you can see/hear a strong spark but still no ignition, do not attempt to strip or replace the gas valve or injectors; this is hazardous work and requires a Gas Safe engineer.

When to call a professional and what to tell them:

- Call a Gas Safe registered engineer if: resets do not clear the problem; there is no gas supply to the boiler; you suspect a faulty igniter, electrode, gas valve, flame sensor, or control board; the condensate pipe is blocked and you cannot clear it safely; or if the boiler locks out repeatedly.

- When you call, give the engineer the exact model, serial number, the T1 code behavior (brief test vs repeated lockout), any other codes shown, what you have already checked (power, gas, pressure, condensate, observed spark), and whether you can hear the fan/pump and spark on start-up.

Important final notes:

- Do not attempt internal electrical or gas repairs yourself. Replacing ignition electrodes, gas valves, PCB, or adjusting gas components must be done by a qualified Gas Safe engineer.

- Limit resets to avoid masking faults. Keep a record/photo of the display and any fault lights for the engineer. If the boiler is unsafe or you smell gas, evacuate and call the emergency gas service immediately.