What does the Worcester Bosch CD error code mean?
On Worcester Bosch Greenstar models displaying a CD fault, the issue is the domestic hot-water temperature sensor (DHW NTC thermistor). The boiler can still heat the radiators but won't reliably produce hot water until the sensor is replaced.
What causes the Worcester Bosch CD fault?
The CD error on a Worcester Bosch boiler is most commonly triggered by:
- A failed DHW NTC thermistor giving an out-of-range reading
- Poor electrical connection at the sensor plug
- Water ingress or scale affecting the sensor pocket
How to fix the Worcester Bosch CD boiler fault
Follow these steps. If the code returns after you have completed them, stop and call a Gas Safe engineer.
- 1.Hot water won't recover until the sensor is replaced — book a Gas Safe engineer.
- 2.Central heating can usually still run in the meantime unless the fault prevents ignition.
Frequently asked questions about the Worcester Bosch CD
What does CD mean on a Worcester Bosch boiler?
CD points to a domestic hot water (DHW) temperature sensor fault. The boiler can't read the hot-water temperature correctly, so it disables hot-water production.
Will I still have heating with a CD fault?
Usually yes — CD affects the hot-water sensor, not central heating. You may lose hot water but the radiators can keep running until the sensor is replaced.