Error 3 red flashes

Safety precautions:

1. If you smell gas, leave the property immediately, avoid using electrical switches or phones inside, and call the gas emergency number and a Gas Safe engineer from a safe location. Do not attempt any DIY fixes.

2. Before carrying out checks switch off the boiler electrically (isolate at the fused spur) if you will be touching any external pipework or condensate, and ensure the area is ventilated. Do not open the boiler casing or touch internal components.

Initial checks a homeowner can do:

1. Check other gas appliances (hob, gas fire) to confirm the gas supply is available. If none are working, check the gas meter or prepayment card/credit and contact your gas supplier.

2. Check the boiler pressure gauge; target pressure for most Baxi systems is about 1.0–1.5 bar when cold. If pressure is low (<1 bar) top up using the filling loop (follow your boiler manual). If pressure is repeatedly low, call an engineer.

3. Inspect the external flue terminal for obvious blockages (birds’ nests, leaves, snow). Clear any debris at a safe ladder height only if you can do so safely.

4. Check the condensate pipe (usually a small plastic pipe from the boiler) for freezing in cold weather. A frozen condensate will stop ignition. If frozen, thaw gently with warm water or a warm cloth — do not use boiling water or open flames.

5. Make sure radiator and system valves are open and that the pump is not obviously seized (you may hear the pump run briefly on demand).

Specific diagnostic and fix steps:

1. Try a controlled reset: find the reset button or selector on the boiler (or follow the manual procedure). Press and hold the reset for 5–10 seconds and allow the boiler to attempt to relight. Wait and observe. Do not repeatedly reset more than two or three times if the fault persists.

2. If a successful reset restores operation, monitor the boiler. If the fault returns, record any conditions when it occurs (cold weather, after low pressure, after power cuts) to give the engineer useful information.

3. If pressure was low, top up the system to about 1–1.5 bar, then reset. If topping up fixes the fault, there may be a leak or faulty expansion vessel—book an engineer.

4. If the condensate pipe was frozen and you have thawed it, reset the boiler and check for normal operation.

5. If the gas supply is confirmed and the flue and condensate are clear but the boiler still shows 3 red flashes after a reset, do not attempt internal repairs. The likely causes now include faulty ignition electrodes, mains leads, flame detector, gas valve or PCB faults.

When to call a professional (Gas Safe registered engineer):

1. If you smell gas or confirm loss of gas supply that is not resolved by the supplier. Call emergency services and your gas supplier immediately.

2. If the boiler remains on 3 red flashes after completing the homeowner checks and a proper reset, or if the fault recurs frequently. Ignition components, flame sensing, gas valve and PCB faults require a qualified engineer.

3. If you are not comfortable performing the safe checks or using the filling loop, or if you cannot safely access the condensate pipe or flue.

Important notes:

1. Do not open the boiler casing or attempt to replace ignition components, seals, or gas valves yourself — these are gas-work items and must be done by a Gas Safe registered engineer.

2. Avoid repeatedly resetting the boiler; repeated lockouts indicate an underlying fault and could cause further damage.

3. When you contact an engineer, provide the fault code (3 red flashes), what initial checks you have done (pressure, condensate, flue, gas supply) and whether the fault is intermittent or continuous. This speeds diagnosis and repair.