Worcester Bosch Boiler Fault Codes
From time to time, your Worcester Bosch boiler may display a fault or error code to warn you that there is something wrong with your boiler or central heating system. When this happens, your boiler might go into what’s called a ‘lockout mode’ which is basically a safety feature that prompts the boiler to shut done when it develops a fault. Worcester Bosch boiler fault codes help your engineer to diagnose problems quicker, so it’s important that you tell them the code when you arrange a call out.
If your boiler display is showing a fault code, please feel free to use the tables below to help identify the issue. Once you understand what the code means, you’ll need to contact a Gas Safe engineer to diagnose the exact cause.
Types of Worcester Bosch Boiler Fault Codes
| FAULT TYPE | WHAT YOU’LL SEE ON THE BOILER DISPLAY |
|---|---|
| Fault Error | An alphanumeric fault code will appear to indicate the fault group (see table below). |
| Locking Error | Your boiler will flash a warning triangle and fault code, as well as a static cause code. Once the fault is fixed, you can press the reset button on your boiler to clear the fault code. |
| Blocking Error | No fault code will appear, even though your boiler will stop operating. To access the info menu to find the cause code, press the spanner/return button. The error will automatically resolve once the fault has been cleared. For example, if the boiler is waiting for an area to cool down, the error will disappear once that area is cool. |
| Cause Error | A cause error code is a three digit number that must be accessed via the info menu, which can be done by pressing the spanner/return button. |
| Maintenance Code | Maintenance codes start with the letter H followed by a number. Although the code is telling you that a qualified engineer is required, a maintenance code that has appeared on the display will not stop your boiler from working. |
Worcester Bosch Boiler Locking Error Codes
| FAULT CODE | CAUSE CODE | POSSIBLE CAUSE |
|---|---|---|
| 9A | 362 | Boiler has been fitted with incorrect HCM (Heat Control Module) |
| 9U | 233 | Code plug is faulty or not connected |
| B7 | 257 | Control board needs replacing |
| C6 | 215 | Fan is running too fast |
| C6 | 216 | Fan is running too slow |
| C7 | 214 | Fan is not running at all |
| C7 | 217 | Either the fan is not running or the airflow is blocked |
| D1 | 240 | Sensor is wet or damaged – the boiler will usually block for 300 seconds before the fault code appears |
| D1 | 241 | Sensor is damaged or disconnected – the boiler will usually block for 300 seconds before the fault code appears |
| D1 | 286 | Boiler is overheating |
| E2 | 222 | Flow sensor has shorted or is damaged |
| E2 | 223 | Flow sensor is damaged or disconnected |
| E5 | 218 or 332 | Primary flow sensor has overheated |
| E9 | 219 | Main heat exchanger has overheated |
| E9 | 220 | Main heat exchanger maximum temperature sensor has failed |
| E9 | 221 | Main heat exchanger maximum temperature sensor has not been recognised |
| E9 | 224 | Flue gas thermostat has overheated |
| EA | 227 | Failure of four attempts at igniting the boiler – will need to wait at least 30 seconds before making another attempt |
| EA | 229 | Established flame has been extinguished – Possible causes include a blocked sump or strong wind into the flue |
| EA | 234 | Gas valve coil is disconnected |
| EA | 261 | No flame has been established during the first 4 seconds of ignition period |
| EA | 338 | Pump is not detecting water – check pressure gauge and re-pressurise to 1 bar |
Worcester Bosch Boiler Blocking Fault Codes
| FAULT CODE | CAUSE CODE | POSSIBLE CAUSE |
|---|---|---|
| A1 | 281 | Low water in the system or none at all – check pressure gauge and re-pressurise to 1 bar |
| C1 | 264 | Fan has stopped working |
| EA | 227 | No flame has been detected – boiler will block during 4 attempts then go to locking fault |
| EF | 349 | Boiler is operating at minimum burner load and there is a greater flow and return temperature than 18 degrees |
| No code | 212 or 213 | Airlock or reduced water content – check pressure gauge and re-pressurise to 1 bar |
| No code | 260 | Sensor is disconnected or no water content – check pressure gauge and re-pressurise to 1 bar |
Whatever problem you’re experiencing with your boiler, you can read out guide to Worcester Bosch Boiler Repairs to find out what you should do next. Whilst some minor issues, such as re-pressurising your boiler can be done without professional assistance, the majority of the faults listed above will require a Gas Safe registered engineer.
