Error E28

Safety precautions:

1) If you smell gas or suspect a leak, leave the property immediately and call your gas emergency number. Do not try to fix a gas leak yourself.

2) Before doing any work on the boiler, switch the boiler off at the control panel and isolate the electrical supply at the wall isolator. If you will be working near the condensate pipe outdoors you do not normally need to turn off the gas unless you are opening or modifying the appliance.

3) Do not pour boiling water onto plastic condensate pipework — use warm water only. Avoid working at height alone; use safe access equipment if the pipe is above ground level.

4) Do not open the boiler casing, touch internal components, or attempt to replace the thermistor, PCB, gas valve or other gas-containing parts unless you are a Gas Safe registered engineer.

Initial checks homeowners can do:

1) Note the exact error and any other indicators (locked-out light, whether heating or hot water is affected). Take a photo of the display if possible.

2) Go outside and inspect the condensate pipe (typically a small plastic pipe running from the boiler to an external drain). Look for frost, ice, or a visible blockage. Also check the external flue terminal for ice, bird nests, leaves or other obstructions.

3) Check for kinks, crushed sections, or disconnections in any visible condensate pipework. If the pipe runs through a driveway or under low areas check those sections.

4) If you can see any damaged or loose external wiring to the boiler, do not touch the wires; photograph and report them to the engineer.

Specific diagnostic and fix steps (homeowner-level):

1) If the condensate pipe is frozen: a) Turn the boiler off and isolate the electrical supply at the wall. b) Warm the frozen section using warm (not boiling) water from a watering can, a warm (not scalding) towel, or a hairdryer on a low setting. Pour/supply water gradually so the pipe warms and ice melts; avoid thermal shock from boiling water. c) Once thawed, wrap the exposed section with insulation (pipe lagging) to reduce re-freezing and consider running the central heating to keep flow moving. d) Restore power and reset the boiler (see reset steps below). If the error clears and the boiler runs normally, monitor for recurrence.

2) If the external flue terminal is blocked: a) Do not insert objects into the flue. Remove visible lightweight debris (leaves, snow) from around the terminal with your hands or a soft brush. b) If birds or a nest are present, do not attempt to remove it yourself — contact a professional as removal may be hazardous and protected species laws can apply.

3) Reset procedure: a) Follow the boiler’s reset procedure — either press the dedicated reset button or use the selector switch to the R (Reset) position for about 5 seconds, or power-cycle the boiler by switching off at the isolator for 30 seconds then back on. b) Watch the display during restart. If the E28 clears and the boiler runs, leave the system operating and monitor. If the fault returns immediately or shortly after, further investigation is required.

When to call a professional (and what they will do):

1) Call a Gas Safe registered engineer if thawing and basic external checks do not clear the fault, if the error returns repeatedly, if you see damaged wiring, or if you suspect a faulty thermistor, control board or internal fault. Do not attempt to replace sensors, PCBs, or gas components yourself.

2) The engineer will safely isolate the boiler, test the flue thermistor and wiring with diagnostic tools, check flue pressures and fans (if applicable), inspect the condensate route internally and externally, and replace faulty components or repair wiring as required. They can also advise permanent fixes to prevent condensate freezing (rerouting, lagging, or frost-heating solutions).

Other practical advice:

1) If you live in a cold location, insulate any exposed condensate pipework and consider a more permanent frost-prevent solution. 2) Keep a record of recurring faults, photos of the external pipework and flue terminal, and the times/dates you see E28 — this helps the engineer diagnose intermittent problems. 3) Never use boiling water on plastic pipes and never attempt internal gas or electrical repairs yourself.

If the E28 persists after taking the safe homeowner steps above, arrange a visit from a Gas Safe registered engineer to diagnose and repair the boiler.