Error E13

Safety precautions:

- Before doing anything isolate electrical supply to the boiler at the switch or isolator. Do not work on gas or internal boiler parts unless you are a qualified Gas-Safe engineer.

- If you smell gas, leave the property immediately and call the gas emergency number.

- Wear gloves and eye protection when handling components and take care with hot surfaces if the boiler has recently run.

Initial checks a homeowner can do:

1. Note the boiler display and exact behaviour (steady E13, flashing, any other codes). Try a simple reset: turn the boiler off at the isolator or mains for 30 seconds, then restore power and observe. Some transient faults clear with a reset.

2. Check system pressure on the boiler pressure gauge. If pressure is very low (<1 bar) the boiler may behave unpredictably; if low, top up the system to the recommended pressure (usually about 1.0–1.5 bar) following the manual. Only top up if you know how to use the filling loop safely.

3. Request central heating (raise the room thermostat or call for heat from the boiler controls) and listen/feel: is the circulation pump running? Are radiators beginning to warm? If the pump runs and radiators warm, the system is circulating which helps narrow the fault toward the flow switch or its wiring.

4. Visually inspect any easily accessible wiring and connectors around the underside of the boiler for loose or corroded connections. Do not disconnect wiring unless the boiler power is isolated.

Specific diagnostic and simple fix steps (only non-invasive actions):

1. If the pump is silent when a heat demand exists, try bleeding a radiator to release trapped air and then try again. Airlocks can sometimes prevent correct flow detection. Bleed radiators starting from the lowest point in the system to remove trapped air.

2. Check that all isolation valves on the boiler and pump are open (if your system has visible service valves). If a motorised zone valve is present, ensure it moves when the boiler calls for heat. A stuck closed zone valve can cause the flow situation the boiler detects.

3. If you can identify the flow switch location from the manual and it is external and accessible (not internal to the boiler casing), isolate power and gently tap the sensor/paddle to try to free a stuck element. Some switches are mechanical and can become stuck with debris. Only do this if the part is clearly external and designed to be touched in the manual; do not open the boiler casing or tamper with internal parts.

4. After any non-invasive action, restore power and attempt another reset/test cycle. Observe whether E13 clears when the pump runs and flow is present.

When to call a professional:

- If E13 persists after resets, pressure checks, bleeding radiators and confirming pumps/valves, stop troubleshooting and call a Gas-Safe registered heating engineer.

- If you find damaged wiring, suspect a failed flow switch, or need to open the boiler casing, a qualified engineer must carry out the repair or replacement.

- If the boiler locks out repeatedly or other fault codes appear alongside E13, call a pro.

Why a professional is needed:

A Gas-Safe engineer will safely test the flow switch, wiring, pump operation and associated controls, replace the flow switch if required, check motorised valves and perform any necessary electrical or gas-side diagnostics. They will also check for system blockages, sludge or pump performance issues that may be causing abnormal switch behaviour.

Final note:

Do not attempt any gas or sealed-component work yourself. E13 can sometimes be a simple stuck paddle or wiring issue you can spot with the above safe checks, but persistent or internal faults require a qualified engineer to ensure safe, correct repair.