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The boiler has attempted to ignite but has not successfully detected a flame, or the flame signal has been lost.
Possible causes can relate to the gas supply, ignition, flame detection or other combustion-related conditions.
E9 is associated with safety-temperature or overheating conditions on applicable Worcester Bosch boilers.
The exact cause depends on your boiler model and may require professional diagnosis if the fault persists.
On applicable Worcester Bosch models, E2 can indicate a problem involving the central-heating flow temperature sensor.
This is generally an internal fault that should be professionally diagnosed.
F0 can indicate an internal or control-related error on applicable Worcester Bosch boilers.
The exact problem depends on the boiler model and any additional cause code displayed.
| Code | General Meaning | What To Do |
|---|---|---|
| A1 | Pump or circulation-related fault on applicable models | Engineer diagnosis may be required |
| A7 | Hot-water temperature sensor fault | Arrange professional diagnosis |
| A8 | Communication or control-related fault | Check model instructions; engineer may be required |
| C6 | Fan or airflow-related fault | Professional diagnosis required |
| C7 | Fan or airflow-related fault on applicable models | Professional diagnosis required |
| D1 | Return temperature sensor fault | Professional diagnosis required |
| D4 | Temperature difference outside expected limits | Professional diagnosis recommended |
| E2 | Heating flow temperature sensor fault | Professional diagnosis required |
| E9 | Safety temperature or overheating-related fault | Allow boiler to cool; seek help if persistent |
| EA | Flame not detected or ignition-related fault | Safe external checks; engineer if persistent |
| F0 | Internal or control-related fault | Professional diagnosis usually required |
| F7 | Flame detected when burner should be off | Professional diagnosis required |
| FA | Flame signal detected after gas shut-off | Professional diagnosis required |
| FD | Reset-related condition on applicable models | Follow model instructions |
Arrange an inspection if:
An EA fault code generally means your Worcester Bosch boiler has not detected a flame when attempting to ignite, or the flame signal has been lost.
There are several possible causes, including problems with the gas supply, ignition or flame detection. The precise cause can depend on your Worcester Bosch model and any additional cause code displayed.
If the EA code returns after following the reset instructions for your boiler, professional diagnosis may be required.
An E9 fault is associated with a safety-temperature or overheating condition on applicable Worcester Bosch boilers.
The boiler may shut down to protect itself when an abnormal temperature is detected. Because several underlying problems can cause an E9 code, the exact cause should be checked against your boiler model and any additional diagnostic code shown.
If the boiler repeatedly displays E9, arrange an inspection rather than continually resetting it.
If a fault code disappears after a reset but later returns, the condition that caused the fault may still be present.
A reset can restart the boiler, but it doesn't repair a failing sensor, circulation problem, ignition fault or another underlying issue. Repeated fault codes are a good reason to have the boiler properly diagnosed.
In many cases, yes. Worcester Bosch boilers have a manufacturer-specified reset procedure that homeowners can follow.
However, the reset method varies between models, so use the instructions for your particular boiler rather than guessing.
If the boiler immediately locks out again or the same fault repeatedly returns, avoid continually resetting it and arrange professional diagnosis.
No. Worcester Bosch has produced many boiler ranges and generations, and their diagnostic systems are not identical.
The meaning of a fault can depend on the boiler model, fault code and accompanying cause code. That's why you should identify your Worcester Bosch model when looking up an error rather than relying only on the letters or numbers displayed.
A fault code identifies the general type of problem detected by the boiler, while an additional cause code can provide more detailed diagnostic information.
This is important because one general fault can have several possible causes. The code displayed on your boiler therefore doesn't always tell you which component needs repairing or replacing.
Low system pressure can prevent some Worcester Bosch boilers from operating correctly.
Check the pressure gauge or display against the recommended operating pressure stated in the instructions for your particular model. If pressure repeatedly drops after being restored, there may be an underlying problem that needs investigating.
Not every code or symbol displayed by a Worcester Bosch boiler indicates a breakdown.
Some displays relate to normal operation, servicing or temporary operating modes. If your boiler appears to be working normally, check the meaning of the display against the user instructions for your particular model before assuming there is a fault.
On applicable Worcester Bosch boilers, SE is a service indication rather than a fault code. It can appear when the boiler has reached its programmed service interval.
If SE appears but the boiler continues operating normally, check the servicing information for your model and arrange a boiler service if required.
You can carry out basic external checks such as checking the controls, power supply and information displayed by the boiler.
However, do not remove the boiler casing or attempt repairs involving internal gas, combustion or electrical components. These should be investigated by an appropriately qualified engineer.
