Fault codes / Girard GSWH-2 / E4

Girard GSWH-2 code E4

What it means: Inlet water thermistor open or shorted.

What to check

Same as E0 but on the inlet side. Reseat, look for corrosion, measure ohms, replace.

Learn the system

• Tank water heaters
• Tankless water heaters
• Water heater gas side

Practice it on a service call

• No hot water on electric
• Water heater lights, then goes out
• Water heater lights then faults

Guided diagnosis

• Water Heater

Other Girard GSWH-2 codes

• Girard GSWH-2 code E0 Outlet water thermistor open or shorted
• Girard GSWH-2 code E1 Ignition failed or flame lost at start
• Girard GSWH-2 code E2 Flame lost while running
• Girard GSWH-2 code E3 Eco (high-limit) switch is open
• Girard GSWH-2 code E5 Blower fault
• Girard GSWH-2 code E6 Outlet water over 140 F for 3 seconds
• Girard GSWH-2 code E7 Linear gas valve open circuit
• Girard GSWH-2 code E8 Air pressure switch fault
• Girard GSWH-2 code E9 Flame sensed before ignition or a short
• Girard GSWH-2 code Fd Freeze protection is active
• Girard GSWH-2 code En Run timer ended

Full field guide: Girard GSWH-2 tankless water heater

Codes come from the maker manuals and public service sheets. Your model's own chart always wins, and LP and 120 volt work belongs to a qualified technician.