BoilerFaultCodesWorcester Bosch E9 Fault Code
The Worcester Bosch E9 fault code means: your boiler has switched itself off because it has become dangerously hot and needs to cool down to prevent damage.. It appears on 42 Worcester Bosch models in our database.
Technical description: Safety temperature limiter in heat exchanger or flue gas temperature limiter has been activated.
What causes the Worcester Bosch E9 fault?
This fault occurs when the internal temperature of the boiler rises above a safe limit, causing the system to shut down to prevent damage. The most common reasons are a lack of water flow due to a seized pump, a blockage in the heat exchanger, or air trapped within the pipework. Effectively, the heat being produced by the burner is not being carried away into your radiators quickly enough.
This fault often appears during the first cold spell of autumn when the heating is turned on after a long summer break, as internal pump components can seize during periods of inactivity.
DIY fix possible
Check the pressure gauge on the front of the boiler; if it is below 1 bar, top it up to 1.5 bar using the filling link.Ensure all radiator valves are fully open to allow water to circulate through the system.Press and hold the 'Reset' button for five seconds to see if the error clears once the boiler has cooled down.
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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.
- 532 / 537 / 542 Repair: £120-250
- 533 Compact
- 535 Compact
- 537i Repair: £120-250
- Bosch Greenstar ZWBR 7-25A
- CDi Classic Repair: £100-280
- CDi Classic Regular Repair: £150-300
- CDi Highflow Repair: £150-350
- Greenstar 24
- Greenstar 25 Si Compact Repair: £150-£300
- Greenstar 25CDi Repair: £120-250
- Greenstar 25HE Repair: £120-£350
- Greenstar 25i (ZWB 7-25) Repair: £120-250
- Greenstar 25Si Compact ErP Repair: £120-350
- Greenstar 27i System Compact ErP Repair: £100-£250
- Greenstar 28
- Greenstar 28CDi Compact ErP Repair: £150-300
- Greenstar 30 CDi System
- Greenstar 30 Si Compact Repair: £150-£300
- Greenstar 30CDi Classic System ErP Repair: £120-350
- Greenstar 30HE Repair: £100-£350
- Greenstar 30i System Compact ErP Repair: £100-£250
- Greenstar 30Si Compact ErP Repair: £120-350
- Greenstar 35 CDi range Repair: £120-£350
- Greenstar 42CDi Repair: £120-350
- Greenstar CDi Classic (2012) Repair: £150-300
- Greenstar CDi Compact Repair: £100-£350
- Greenstar Heatslave II Repair: £150-300
- Greenstar Highflow Repair: £150-300
- Greenstar i Repair: £90-280
- Greenstar R 28 HE System Repair: £120-350
- Greenstar R29 40 HE Repair: £150-350
- Greenstar System Repair: £120-250
- Greenstar ZWB7 Repair: £150-350
- Highflow 400 Electronic BF
- Highflow 440 CDi Repair: £150-250
- Highflow 550 CDi Repair: £150-250
- Highflow CDi Repair: £120-250
- R30 HE Plus Repair: £120-350
- 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 535 Compact manual (PDF)
- Worcester Bosch 537i manual (PDF)
- Worcester Bosch Bosch Greenstar ZWBR 7-25A manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026