A Worcester Bosch fault code tells you why the boiler has stopped or locked out. Some, such as low pressure or a frozen condensate pipe, you can safely check yourself; most others need a Gas Safe registered engineer. Find your code below. Most Greenstar combi and system boilers show a two-character fault code with a three-digit cause code, for example EA 227. A flashing code with a warning triangle is a locking fault that needs a reset; some faults block the boiler without showing a code. Older and newer ranges use different codes.
Smell gas, or a carbon monoxide alarm is sounding? Do not reset the boiler. Open windows, turn off the gas at the meter if it is safe to do so, leave the building and call the free gas emergency line on 0800 111 999. What to do →
Worcester Bosch fault codes and what to do
EA 227You may be able to fix this
What it means: No flame detected after ignition: the boiler tried to light four times and failed.
What to do: Check other gas appliances work and, on a prepayment meter, that you have credit. In freezing weather, check the condensate pipe is not frozen. Then press reset once.
EA 229You may be able to fix this
What it means: The flame went out while the boiler was running. A blocked condensate trap or strong wind into the flue can cause it.
What to do: Check the condensate pipe outside is not frozen or blocked, then reset once. If it returns, call an engineer.
EA 338You may be able to fix this
What it means: Too many short burner starts, often because the pump is not detecting enough water.
What to do: Check the pressure gauge. If it is below 1 bar, repressurise to about 1 bar using the filling loop, as shown in your manual.
A1 281You may be able to fix this
What it means: The pump is stuck or running in air: little or no water in the system.
What to do: Check the pressure gauge and repressurise to about 1 bar. If the pressure keeps dropping, there may be a leak: call an engineer.
LoPrYou may be able to fix this
What it means: Low system pressure (shown on newer Greenstar models such as the 8000 Life).
What to do: Top up the heating water to the pressure shown in your manual using the filling loop.
C6 215 / 216Engineer needed
What it means: Fan fault: the fan is running too fast (215) or too slow (216).
What to do: Do not open the boiler. A Gas Safe engineer needs to check the fan and flue.
E9 219Engineer needed
What it means: The main heat exchanger has overheated (maximum 105°C).
What to do: Low water pressure or a blocked system can cause overheating. Check the pressure, then call an engineer if it returns.
E9 224Engineer needed
What it means: Flue gas thermostat overheat.
What to do: Switch the boiler off and call a Gas Safe engineer.
D1 240 / 241Engineer needed
What it means: Return temperature sensor fault: the sensor is wet, disconnected or damaged.
What to do: Needs an engineer. The boiler blocks for a few minutes before locking out.
E2 222 / 223Engineer needed
What it means: Flow temperature sensor shorted, disconnected or damaged.
What to do: Needs a Gas Safe engineer to test or replace the sensor.
D5Engineer needed
What it means: Condensate pump failure (Greenstar CDi Highflow).
What to do: Needs an engineer.
H codes (e.g. H13)You may be able to fix this
What it means: Maintenance codes. They do not stop the boiler. H13 usually means the annual service is due.
What to do: Book a boiler service; there is no need for an emergency callout.