Girard GSWH-2 tankless water heater fault codes
Girard GSWH-2 (Lippert) tankless, 42,000 BTU, very common in towables. Needs 12V DC (under about 3 A). Fires on LP only. Also sold under other RV brand names, so check the label.
Girard GSWH-2 code E0
Outlet water thermistor open or shorted. Reseat the sensor plug. Look for water or corrosion on it. Measure ohms: a good sensor gives a steady value that moves as it warms. Open or zero: replace it.
Girard GSWH-2 code E1
Ignition failed or flame lost at start. Gas valve open, tank has LP, igniter gap and condition, debris on the burner, low gas pressure, air in the lines. Test with a manometer while it fires.
Girard GSWH-2 code E2
Flame lost while running. Low gas pressure at high fire, poor flame sensor or ground, vent recirculation, wind, regulator.
Girard GSWH-2 code E3
Eco (high-limit) switch is open. Meter on the blue wires at CN9 with power off. OPEN = the ECO is bad, replace it. CLOSED = the board is the likely fault. Also find out why it overheated.
Girard GSWH-2 code E4
Inlet water thermistor open or shorted. Same as E0 but on the inlet side. Reseat, look for corrosion, measure ohms, replace.
Girard GSWH-2 code E5
Blower fault. Check the blower plug at CN1, debris in the blower, and 12V and ground at the blower while it runs. Replace the blower if it is jammed or open.
Girard GSWH-2 code E6
Outlet water over 140 F for 3 seconds. Hot water is entering the heater (bypass valve passing, recirculation), or the outlet thermistor reads wrong, or the flow is very low.
Girard GSWH-2 code E7
Linear gas valve open circuit. Check the red and white valve wires and plug. Coil should read about 80 to 100 ohms. Open: replace the valve.
Girard GSWH-2 code E8
Air pressure switch fault. Check the hose for cracks or water, the small pickup tube for blockage, then suck gently on the hose and listen for the switch click. Blocked vent also trips it.
Girard GSWH-2 code E9
Flame sensed before ignition or a short. Residual gas flame, a sticking gas valve, or a shorted sensor lead. Check the gas solenoid and the flame sensor wiring.
Girard GSWH-2 code Fd
Freeze protection is active. The freeze thermostat turns on near 38 F and off near 58 F. Normal in cold weather. Drain the heater for storage.
Girard GSWH-2 code En
Run timer ended. The 20 minute run timer expired. Close and reopen the tap to restart.
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Practice it on a service call
Guided diagnosis
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.