Overview
The EA 227 (No flame detected / insufficient ionisation current) on a Worcester Bosch GB162 means the boiler attempted ignition several times but did not detect a flame signal from the flame sensing electrode, so the control has gone into a safety lockout. The boiler measures a small ionisation current from the flame to confirm combustion; if that current is too low or absent the controller will shut the appliance down to prevent unburnt gas being released. This fault commonly occurs because the burner failed to light or the flame sensor/ignition circuit cannot detect the flame. Typical causes include loss of gas supply (meter, isolation valve, or network issue), frozen or blocked condensate or condensate trap affecting normal operation, a dirty or faulty flame sensing electrode or ignition lead, blocked pilot/jet, airflow or flue restrictions, moisture damage to PCB/electrical components, or a faulty gas valve. Severity is moderate to high because the fault stops heating and hot water and is a safety lockout; it is not an emergency by itself unless you smell gas. Some preliminary, non-invasive checks are safe for homeowners, but diagnostic and repairs to gas, ignition or internal electrical parts must be carried out by a Gas Safe registered engineer.
Possible Cause: An insufficient ionisation current was measured following ignition of the burner.
Troubleshooting Steps
Safety precautions:
- If you smell gas, do not operate the boiler or electrical switches. Open windows, leave the property immediately and call the gas emergency number (or your supplier) from a safe location. Do not attempt internal gas repairs.
- Only perform non-invasive checks. Any work on gas valves, burners, ignition, or internal electrical components must be done by a Gas Safe engineer. Repeated resetting of a locked-out boiler is not recommended; this can mask a dangerous fault.
Initial homeowner checks (safe to do):
1. Check other gas appliances (hob, oven, gas fire). If they don’t light, suspect a gas supply issue or frozen gas meter and contact your gas supplier. If you use a prepay meter, ensure credit/top-up.
2. Check the boiler display and manual for the reset procedure. Perform a single reset following the manufacturer’s instructions and observe behaviour. If EA 227 returns immediately or after a few attempts, stop and call an engineer.
3. Inspect the external condensate pipe (white plastic pipe running outside). In cold weather it can freeze. Thaw gently with warm (not boiling) water and clear any visible blockage; once thawed, reset the boiler. Lag (insulate) the pipe to prevent recurrence.
4. Check boiler pressure on the gauge; typical cold pressure is around 1.0–1.5 bar. Very low pressure can affect operation. If pressure is low, follow the manual to top up the system. If you cannot or are unsure, call an engineer.
5. Look for obvious signs of water leaks or moisture around the boiler casing and beneath it. If you find an active leak, turn the boiler off electrically, isolate the mains water if safe to do so, and call an engineer.
6. Check vents, flue outlet and air intake for obvious blockages (birds’ nests, debris). Do not remove flue covers that require tools or access panels you are not qualified to open.
Further diagnostic steps to report to an engineer (do not open or touch internals unless qualified):
1. Note the exact sequence: does the boiler try to ignite multiple times (you may notice clicking/ignition attempts) before locking out? How many attempts and timing? Note any other fault codes or flashing LEDs. This information speeds diagnosis.
2. If thawing the condensate pipe and a single reset brings the boiler back to normal, monitor for repeat faults and consider insulating the pipe and booking a service.
3. If the boiler tries to ignite but there is no flame, likely causes an engineer will check: ignition electrode/lead (dirty, cracked, incorrectly positioned), flame-sensing electrode condition, blocked burner jet(s), faulty gas valve or incorrect gas pressure, blocked flue or restricted air supply, or moisture damage to the PCB/ignition circuitry.
4. If you suspect moisture ingress (history of leaks or condensation), isolate and turn off the boiler and contact an engineer to inspect the heat exchanger, pump seals and PCB. Moisture on electronics will require professional testing and likely component replacement.
When to call a Gas Safe registered engineer:
- EA 227 persists after the safe homeowner checks above (condensate thaw, reset, gas supply check, pressure).
- Any sign of gas smell, leak, persistent pressure loss, or evidence of internal water leaks.
- If the fault is traced to ignition leads, flame electrode, burner nozzle, gas valve, fan/flue assembly or PCB—these are gas/appliance components that legally and safely must be handled by a Gas Safe engineer.
What to tell the engineer and preparation:
- Provide the exact fault code (EA 227), how many ignition attempts you observed, whether thawing the condensate pipe or resetting changed anything, whether other gas appliances are working, current boiler pressure, and any visible leaks or external blockages. Have the boiler model and serial number ready if possible.
Preventive advice:
- Annual service by a Gas Safe engineer to clean electrodes/jets, check gas pressure and seals. Insulate external condensate pipe and protect external gas meters. Avoid repeated reset cycles and get a qualified diagnosis if the fault recurs.
Note: This guidance is for initial safe checks only. Do not attempt internal gas, burner or PCB repairs unless you are a Gas Safe registered engineer.
Helpful Resources
Boiler Manual
Download the official PDF manual for the Worcester Bosch GB162 Boiler.