Error E154

Safety precautions:

1. If you smell gas, turn off the gas supply at the meter, get everyone out of the property and call the gas emergency number immediately. Do not attempt repairs.

2. Isolate the boiler electrical supply if you need to work close to the casing (switch off the fused spur or consumer unit circuit). Do not remove the boiler cover or touch internal components unless you are Gas Safe registered.

3. Wear gloves when checking pipework — flow pipes can be very hot.

Initial checks a homeowner can do:

1. Note the exact error code and any other display messages. Take a photo of the display for the engineer if needed.

2. Check the boiler water pressure on the gauge. Baxi boilers normally operate between roughly 1 and 3 bar; aim for around 1–1.5 bar for a cold system. If pressure is low (below about 0.8–1.0 bar or below the boiler’s specified minimum), repressurise via the filling loop following the boiler manual instructions.

3. Check that heating demand is selected (room/stat is calling for heat) or request hot water to see if the fault appears under both modes.

4. Bleed radiators to remove trapped air which can cause poor circulation.

5. In freezing weather, check that any external condensate pipe is not frozen or blocked.

Basic diagnostic and DIY steps (do not open the boiler casing or attempt internal repairs):

1. Reset the boiler: find the reset button (often marked with a flame or labelled reset) and press and hold for 5–10 seconds. Wait for the boiler to attempt restart. A single reset is safe; do not keep repeatedly resetting if the fault returns immediately.

2. After reset, run the heating or hot water and observe. If E154 clears and the system runs normally for a sustained period, the fault may have been a temporary sensor glitch or communication blip. Monitor pressure over the next 24–48 hours.

3. With the heating running, carefully feel the flow and return pipes at the boiler (outside the insulation). The flow pipe should be noticeably hotter than the return. If both pipes are cold or nearly the same temperature while the boiler is calling, this suggests no circulation (pump issue, closed valve, or blockage).

4. Listen at the boiler for the pump running (a faint humming/vibration). If you suspect the pump has failed (no noise/vibration and no circulation), do not attempt to dismantle it — record what you observed and call an engineer.

5. If you have recently bled radiators or topped up pressure, recheck the pressure and repeat a reset to see if the fault clears.

6. Check visible sensor wiring (only externally accessible wiring) and pipework for loose connectors or obvious damage. Do not open the boiler to access internal wiring; note any visible issues and photograph them for the engineer.

When to call a professional (Gas Safe engineer):

1. If E154 persists after initial checks and a reset.

2. If the boiler locks out repeatedly or you have no heating/hot water despite correct pressure and normal demand settings.

3. If you suspect pump failure, sensor failure, wiring faults behind the casing, or PCB communication faults.

4. If you smell gas or detect leaks of any kind.

Information to give the engineer:

1. Exact error code (E154) and any other messages, when it appears (CH or DHW mode), and any recent activity (radiator bleeding, topping up, freezing conditions).

2. System pressure reading and whether you topped up.

3. What you tried (reset, bled radiators, checked condensate pipe).

Important warnings:

1. Do not attempt to replace temperature sensors, the pump, the PCB, or any gas components yourself unless you are Gas Safe registered. Opening the boiler and attempting repairs risks gas leaks, electric shock and invalidating warranties.

2. Do not repeatedly reset the boiler if the fault returns quickly — this can cause further damage and is not a safe long-term solution.

If the fault persists after the homeowner checks and a single reset, arrange a visit by a Gas Safe engineer. They will perform safe electrical and gas checks, confirm whether the flow/return sensors, wiring, pump or PCB need replacement, and restore the boiler to safe working order.