BoilerFaultCodesWorcester Bosch 235 Fault Code
The Worcester Bosch 235 fault code means: your boiler’s internal control parts are speaking different languages because a newer component has been installed that is incompatible with the older system.. It appears on 21 Worcester Bosch models in our database.
Technical description: The KIM (boiler identification module) is too new for the burner control unit
What causes the Worcester Bosch 235 fault?
This fault occurs when a replacement part is installed that uses a newer software version than the boiler's main brain can understand. It is almost always triggered following a recent repair where a new KIM identification module or burner control unit was fitted without checking their version compatibility. Essentially, the boiler has been given a component that is too modern for the rest of its internal system to work with.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Worcester Bosch models that show the 235 fault code
Click a model for the full fault code list and model-specific repair notes.
- 1000 Repair: £150-300
- 24 RSF Repair: £180-350
- 26 CDi Xtra Repair: £180-350
- 30i Junior Repair: £250-450
- 35 RSF Repair: £120-£350
- CDi Classic Repair: £180-450
- Danesmoor Repair: £180-450
- GB162 Repair: £250-550
- Greenstar 12i System Repair: £150-300
- Greenstar 2000 Repair: £120-250
- Greenstar 27CDi Repair: £120-250
- Greenstar 28CDi Repair: £120-250
- Greenstar 4000 Repair: £150-300
- Greenstar 8000 Repair: £120-250
- Greenstar 8000 Life/Style Repair: £120-£450
- Greenstar 8000 Style Repair: £150-300
- Greenstar i Repair: £150-300
- Heatslave Repair: £180-450
- Hideaway Repair: £180-450
- Junior 24i Repair: £250-£450
- Junior 28i Repair: £250-450
Source
Worcester Bosch 235 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026