Error E10

Safety first

1) If you smell gas, evacuate the property immediately and call the gas emergency number — do not touch the boiler. 2) Before touching the boiler controls, turn off the boiler electrically if you are going to make any internal checks or work (switch off at the isolator or fuse). 3) Never remove sealed covers, work on gas pipework, or attempt to replace gas-carrying or electrical components unless you are a Gas Safe registered engineer.

Initial homeowner checks (safe and simple)

1) Record the exact display: note E10 plus any other symbols or flashing lights. Take a photo. 2) Check system pressure on the boiler gauge. Baxi boilers typically run around 1.0–1.5 bar cold. If below about 0.8 bar or near 0.0–0.5 bar, top up using the filling loop (see boiler manual) until about 1.0–1.5 bar, then close the valves. 3) Bleed radiators: use a radiator key to vent air from the highest radiators first until water flows steady, then re-check pressure and repressurise if necessary. 4) Check that thermostats, room stat and programmer are calling for heat (set room thermostat higher than room temperature and set programmer to demand CH). 5) Check radiator valves and any zone/lockshield valves are open. 6) Reset the boiler once after performing the above: use the boiler reset procedure in the manual (hold reset for ~5–10 seconds) and watch whether the error clears.

Diagnostic checks you can safely perform

1) Listen and feel for the pump: when the heating is called, you should hear the pump motor running (a soft whir or vibration) and pipes near the pump should get warm as flow starts. If the pump is completely silent and you have power to the boiler, that indicates a pump or PCB/output problem. 2) Check for cold/hot pattern on radiators: if boiler fires but radiators stay cold, this points to circulation issue (pump, diverter valve, blockage or airlock). 3) Watch for pressure behaviour: with heating on, does pressure drop quickly? Rapid pressure loss indicates leak or failed expansion vessel/pressure sensor — call a pro. 4) If you have an accessible magnetic filter or external filter, check for heavy sludge blocking flow (only if the filter is designed to be user-serviced and isolated first). If unsure, leave for the engineer.

What to try next and what to avoid

1) If low pressure: top up to 1–1.5 bar and restart. If pressure drops repeatedly, do not keep repressurising repeatedly — get a professional. 2) If radiators have air: bleed radiators and repressurise once. 3) If pump appears to be stuck and you are competent with basic safe isolation (electrical off), you can try briefly to free a jammed pump by running the boiler after isolating power and following manufacturer guidance — however, do not open or dismantle the pump or remove electrical connections unless qualified. 4) Do not keep resetting the boiler continuously — multiple resets can cause further problems and hide underlying faults.

When to call a professional (and what to tell them)

1) Call a Gas Safe registered engineer if: the E10 returns after basic checks; the pump does not appear to run; pressure loss is persistent or unexplained; radiators remain cold after bleeding and repressurising; or you find signs of leaks or electrical faults. 2) When you call, provide: boiler model (Baxi Avanta), serial number, exact error code (E10) and any secondary codes/symbols, what you have already tried (pressure reading, bleeding, resetting), and whether you smell gas. 3) Ask the engineer to check pump operation, flow/pressure sensors, diverter valve operation, magnetic filter/heat exchanger blockage, expansion vessel and PCB outputs.

Final notes

1) Small circulation fixes (topping up pressure, bleeding radiators, opening valves, one reset) are often DIY. Anything involving gas, internal components, pump replacement, sensor replacement, or persistent faults must be handled by a Gas Safe registered engineer. 2) Keep records of service visits and any repeated fault occurrences — repeated E10 faults need a professional diagnosis to prevent damage to the boiler.