Error E.01 – .17

Safety precautions:

- If you smell gas, do not touch the boiler or any electrical switches; ventilate the area, turn off gas at the meter (if you know how) and call your gas emergency service immediately.

- Do not open the boiler casing, work on wiring, or attempt gas or combustion component repairs unless you are a qualified Gas Safe engineer.

- Isolate electrical power at the fused spur before touching any internal parts. Allow hot components to cool before feeling the pump or pipes.

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

1. Record the full error code and any other display text. A photo of the display is useful for an engineer.

2. Try a reset: press and hold the boiler reset button for 3–10 seconds and watch what happens. If the code clears but returns, proceed with checks below.

3. Check system pressure on the boiler gauge. Aim for roughly 1.0–1.5 bar when cold. If pressure is below 0.5 bar the boiler may not run; use the filling loop to repressurise to around 1–1.5 bar following your boiler manual. After topping up, reset and test.

4. Ensure the heating is actually calling for heat: set the thermostat/programmer to demand CH and set the boiler to heating mode so the pump should run.

5. Check radiator valves and TRVs are open and check for obvious airlocks. Bleed radiators from top floor down to remove trapped air; after bleeding, re-check pressure and top up if needed.

6. Listen and feel (carefully) for the pump: with the boiler powered and calling for heat, stand close to the boiler and listen for a low humming or ticking from the pump. If safe to do so, feel the pump casing briefly (it may be hot). No sound and completely cold when the boiler is calling for heat suggests the pump may not be running.

Specific diagnostic and fix steps you can attempt safely:

1. If pressure was low and you topped up, reset the boiler and confirm whether circulation resumes. If this fixed it, monitor pressure over the next days; repeated pressure loss indicates a leak or failed expansion vessel—call an engineer.

2. If radiators remain cold but the pump is running (you can hear vibration), try bleeding radiators to clear airlocks and recheck flow. If the pump runs but some radiators heat partially, you may have partial blockage or a stuck diverter valve (combi boilers) which needs professional attention.

3. If you suspect a seized pump (boiler silent, no vibration) do not try to dismantle the pump unless you are qualified. Some engineers may be able to free a stuck rotor, but replacement is often required.

4. If you suspect a sensor or wiring fault (intermittent faults, obvious loose connector visible externally, or the error returns immediately after reset) do NOT open or probe wiring unless you are competent and the power is isolated. Sensor checks and replacements must be done by a Gas Safe engineer.

When to call a Gas Safe engineer:

- The E.01 – .17 fault persists after resets, pressure topping up, radiator bleeding and ensuring valves are open.

- The pump does not run or is noisy/overheating, or you suspect it is seized.

- The fault looks electrical (intermittent codes, other PCB errors) or you see loose/burnt wiring or smell burning.

- Repeated low pressure, visible leaks, or diverter/valve failures suspected.

- You are not comfortable performing the checks above.

Information to have ready for the engineer:

- Full boiler model and serial number, exact error code (E.01 – .17) and a photo of the display.

- What you have already tried (reset, repressurised, bled radiators, etc.) and whether the fault is constant or intermittent.

- Recent work on the system or any signs of leaks.

Summary: try safe, non-invasive checks first (reset, check pressure, open valves, bleed radiators, listen for pump). If the boiler still reports E.01 – .17 or if you suspect a failed pump, blocked heat exchanger, sensor or wiring fault, stop and call a Gas Safe registered engineer to diagnose and repair. Do not attempt internal electrical or gas-side repairs yourself.