BoilerFaultCodesWorcester Bosch E9 Fault Code
The Worcester Bosch E9 fault code means: your boiler has sensed that it is getting dangerously hot and has shut itself down to prevent damage or overheating.. It appears on 32 Worcester Bosch models in our database.
Technical description: Safety temperature limiter in CH flow or flue gas temperature limiter has operated
What causes the Worcester Bosch E9 fault?
This fault occurs when the internal sensors detect that the water or exhaust gases have reached a dangerously high temperature. The most common reason is a lack of water circulation, often caused by a failed internal pump or a blockage in the system pipework that prevents heat from being carried away from the burner. It can also happen if there is an air lock in the heat exchanger or if the sensors themselves have developed a fault.
This fault often appears during the first cold spell of autumn when the heating is turned back on after months of inactivity, as internal pumps are prone to seizing during the summer.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A cover plan would handle faults like E9: no call-out fees, no surprise bills.
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Worcester Bosch models that show the E9 fault code
Click a model for the full fault code list and model-specific repair notes.
- 24/28/35 CDi MkII Repair: £150-300
- 532 / 537 / 542 Repair: £120-250
- 537i Repair: £120-250
- CDi Classic Repair: £100-280
- CDi Classic Regular Repair: £150-300
- CDi Highflow Repair: £150-350
- CDi RSF Repair: £150-300
- Greenstar 12i System Repair: £120-£350
- Greenstar 25CDi Repair: £120-250
- Greenstar 25HE Repair: £120-£350
- Greenstar 25i (ZWB 7-25) Repair: £120-250
- Greenstar 28CDi Repair: £150-300
- Greenstar 30CDi Classic System ErP Repair: £120-350
- Greenstar 30HE Repair: £100-£350
- Greenstar 30i Repair: £120-£350
- Greenstar 35 CDi Repair: £120-£350
- Greenstar 42CDi Repair: £150-300
- Greenstar CDi Compact Repair: £100-£350
- Greenstar Heatslave II Repair: £150-300
- Greenstar i Repair: £90-280
- Greenstar R29 40 HE Repair: £150-350
- Greenstar Ri Repair: £100-£350
- Greenstar Si Combi / i System Repair: £120-350
- Greenstar ZWB7 Repair: £150-350
- Hideaway 90 Repair: £120-280
- Highflow 440 CDi Repair: £150-250
- Highflow 550 CDi Repair: £150-250
- Highflow CDi Repair: £120-250
- Ri 25 HE Repair: £150-350
- Worcester 25/30 HE Repair: £120-350
- ZB 7 27 HE Repair: £150-300
- ZWB 7-25 Repair: £150-350
Source
Worcester Bosch E9 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
- Worcester Bosch 24/28/35 CDi MkII manual (PDF)
- Worcester Bosch 532 / 537 / 542 manual (PDF)
- Worcester Bosch 537i manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026