HVACopediaBosch · Boiler
8.E Service function 8.E - restore factory settings
What the display is showing
Resets all boiler parameters, including all service functions, to factory settings. The boiler restarts with defaults. Afterwards re-enter the values written in the commissioning report.
Applies to: Greenstar ZBR/ZWB 21-42-3A wall-hung boilers and ZWB 28-42-3A combis
What to do
- Reach the second level and scroll to 8.E
- Press the emissions test button; the display shows 00
- Hold the emissions test button until the confirmation appears
Models that show this code
4 models in Bosch Greenstar
Other codes on the same units
- 7.E Service function 7.E - building drying function
- 7.b Service function 7.b - 3-way valve to center position
- 8.A Service function 8.A - software version
- 8.C Service function 8.C - gas burner control (GFA) status
- 8.F Service function 8.F - permanent ignition test
- 8.b Service function 8.b - code plug number
- 8.d Service function 8.d - gas burner control (GFA) fault
- 9.A Service function 9.A - constant operating mode
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Source: Bosch Greenstar wall ZBR-ZWB 21-42-3A service 6721853955 (2025-11) (same content in combi service 6721853953), 11.3 Description of the service functions pp.59-64. Summarized in our own words; check the original manual for your model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.