Error E26

Safety precautions:

1. If you smell gas: turn off the gas at the meter or cylinder, extinguish naked flames, do not operate electrical switches, ventilate the area and call your gas emergency number immediately.

2. If you are not sure it is a gas leak but suspect unsafe operation, leave the property and call a professional. Do not attempt internal repairs or remove the boiler cover.

3. Before doing any visual checks, switch the boiler to standby or turn it off at the isolator to avoid repeated restart attempts while you inspect.

Initial checks a homeowner can do (visual and non-invasive):

1. Note the displayed fault, the time it appeared and any pattern (only during very cold weather, during/after heavy rain, after refilling gas cylinders, etc.). Photograph the error code display to give to the engineer.

2. Check external flue and air intake terminals (these are usually plastic pipes on the outside wall). Look for obvious blockages: bird nest, leaves, wasp nests, heavy snow or ice, garden waste or debris. Remove loose debris by hand or with gloves; do not insert tools deep into the terminal.

3. Check that any external condensate pipe run is not frozen or blocked (this is usually a small plastic pipe running from the boiler to outside). In cold weather a frozen condensate is a common cause. Thaw gently by pouring warm (not boiling) water along the external pipework, or wrap a warm towel/hot water bottle around the frozen section until thawed. Consider insulating the pipe to prevent recurrence.

4. Confirm gas supply: check other gas appliances (hob, oven, gas fire) to see if they’re operating normally. If using LPG, check cylinder level and changeover status. If multiple gas appliances are weak or won’t light, contact your gas supplier; do not attempt to adjust gas pressure yourself.

5. Check that the boiler condensate trap (if accessible externally) and any visible drains are clear and not overflowing. If you see water pooling at the boiler base or condensate spill, do not operate the boiler until cleared.

6. Once you have made safe, basic checks and cleared any external blockage or thawed condensate, restore power and attempt a single reset of the boiler using the reset procedure in the manual. If the boiler attempts to light and runs normally, monitor it for recurrence. Do not repeatedly reset the boiler more than once or twice if fault persists.

Specific diagnostic steps for the installer or to prepare information for the engineer (do not attempt unless qualified):

1. Record number of lockouts and any allied error history. An engineer will check flame signal strength, ignition electrode condition and spark gap, and flame sensor continuity.

2. The engineer will measure gas inlet and manifold pressures to check for low supply, especially for LPG systems, and verify correct burner/valve operation.

3. The fan and air-pressure/flow sensing system will be checked to confirm adequate combustion air delivery and that the flue is evacuating gases properly (obstructed flue, fan failure or restricted heat exchanger can cause dropout).

4. The condensate drainage path, condensate trap and any internal drains will be inspected and cleared or replaced if damaged; frozen external runs will be insulated or rerouted.

5. If combustion and gas supply are OK, the engineer will test the control box, flame detection circuit and ignition components and replace faulty parts (fan, gas valve, PCB, electrodes or flame sensor) as required.

When to call a professional and next steps:

1. Call a Gas Safe registered engineer if the E26 fault persists after your basic external checks and a single reset, or if you are unable to safely clear an external blockage/ice, or you suspect issues with gas supply or internal components.

2. If you smell gas or suspect a leak, call the gas emergency number immediately rather than trying troubleshooting.

3. Provide the engineer with the fault code, the actions you have already taken (cleared flue, thawed condensate, checked gas supply, reset attempts) and any photos of the external terminals and condensate pipe to speed diagnosis.

Do not attempt to open the boiler casing, adjust gas pressures, replace gas valves, or change internal electrical/combustion components yourself. Those activities require Gas Safe qualified personnel. The steps above are intended to help identify common, safe-to-carry-out causes (external blockages, frozen condensate, empty LPG) and to give the engineer useful diagnostic information.