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Worcester Bosch boiler fault codes
Common Worcester Bosch codes for Greenstar i, Ri, Si Compact, CDi Compact, 2000, 4000 and 8000 boilers, what they mean and what to do.
Worcester Bosch Greenstar boilers show a two-part code: a letter and number on the display, and a three-digit cause code, such as EA 227. Newer models show it alongside a flashing light. These are the codes we are called out for most.
| Code | What it means | What to do |
|---|---|---|
| EA 227 | No flame detected, or the flame was lost while running. | Check your gas supply and, in cold weather, the condensate pipe outside. Press reset once. If it locks out again, book a repair. Engineer needed if it returns |
| CE 207 | Water pressure too low. | Top up the pressure to about 1 to 1.5 bar using the filling loop. If it drops again within days, book a repair. You may be able to fix this |
| E9 224 | Overheat. The safety limiter or flue thermostat has tripped. | Often caused by low pressure, a pump fault or blocked heat exchanger. Check the pressure, then book a repair. Engineer needed if it returns |
| C6 215 | Fan speed fault. The fan is running too fast or too slow. | Needs an engineer to check the fan and flue. Engineer needed if it returns |
| C7 | Fan not running at start-up. | Needs an engineer to check the fan and its wiring. Engineer needed if it returns |
| A1 281 | Pump stuck, or air in the system. | Bleed the radiators and check the pressure. If the code stays, the pump needs freeing or replacing. Engineer needed if it returns |
| E2 | Flow temperature sensor fault. | A faulty sensor or connection. Book a repair visit. Engineer needed if it returns |
| D5 | Condensate pump fault (some Highflow models). | Check the condensate pipe is clear and not frozen, then book a repair if it returns. Engineer needed if it returns |
Codes and their meanings can vary between models and software versions, so check your boiler’s manual too. Never open the boiler casing yourself.
How to top up the pressure
Low pressure is the most common cause of a Worcester Bosch lockout. With the boiler cold, open the filling loop valves slowly until the gauge reads about 1 to 1.5 bar, then close them fully. Your manual shows where the filling loop is on your model. Read our full guide.
When to book an engineer
- The same code comes back after one reset
- The pressure keeps dropping after you top it up
- You see a false flame, flue or gas valve code
- There is water leaking from the boiler
Worcester Bosch questions
What does EA 227 mean on a Worcester Bosch boiler?
No flame detected, or the flame was lost while running. Check your gas supply and, in cold weather, the condensate pipe outside. Press reset once. If it locks out again, book a repair.
How do I reset a Worcester Bosch boiler?
Most models have a reset button or a dial position marked reset. Press or turn it once, and wait a few minutes for the boiler to try again. Check your manual for your model. If the code returns, do not keep resetting it.
Do you repair Worcester Bosch boilers?
Yes. Our Gas Safe engineers repair Worcester Bosch boilers across South London. A repair visit is £90 including the first hour.