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Bosch · Tankless water heater

EF Wrong gas type configured

High severity Bosch Greentherm T9800 SEBosch Greentherm T9900 SE

What the control is telling you

LP gas is detected while the unit is set for natural gas.

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

Likely causes

  • Gas type setting does not match supply

Test and repair steps

  1. Check and correct the gas type setting.

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

  • CE Flue blockage during operation (siphon pressure)
  • CF Flue blockage during operation (insufficient air)
  • EA Ignition failure
  • EB Control unit internal error
  • EC Flame lost during operation
  • EE Gas valve modulation coil disconnected
  • FA Gas leak in the gas path
  • FC Touch key held over 20 seconds

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Source: Bosch Greentherm T9800 SE 160/199 installation 6720816815 (06.2023), Table 24 Error code diagnostics, p.65-69; Bosch Greentherm T9900 SE 160/199 | i 199 installation 6 720 813 635 (2024-06), section 9.1 Error code diagnostics, p.68-73. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

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.