Bosch · Tankless water heater

Burner symbol Burner status symbol - burner on

Normal status Bosch Greentherm T9800 SEBosch Greentherm T9900 SE

What the display is showing

The burner status / error symbol on the display lights to show the burner is on. The same position shows an error symbol when a fault is active.

Applies to: Greentherm T9800 SE 160/199 and T9900 SE 160/199 tankless water heaters

Models that show this code

6 models in Bosch Greentherm T9800 SE, Bosch Greentherm T9900 SE

Greentherm T9800 SE 160Greentherm T9800 SE 199Greentherm T9800 SEC 199Greentherm T9900 SE 160Greentherm T9900 SE 199Greentherm T9900 i 199

Other codes on the same units

AD Power derate warning
AU AU technical settings (service mode)
BB Fan calibration after missed ignitions
BC Repeated fan calibration with similar values
CA Water flow above 9.2 gpm
CE Flue blockage during operation (siphon pressure)
CF Flue blockage during operation (insufficient air)
DH DH data history

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Source: Bosch Greentherm T9800 SE 160-199 installation 6720816815 (06.2023), 6.2 Power p.45; T9900 SE 160-199 installation 6 720 813 635 (2024-06) same section. 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.