GE electric heat pump water heater displays F1 and will not heat water properly.

Safety first: Turn OFF power to the water heater at the breaker panel and verify with a non-contact voltage tester before removing any covers.

Steps to check and address F1:

• Access the control compartment: Remove the front access panel on the GE heat pump water heater to expose the control board and wiring.
• Inspect the tank sensor wiring: Locate the tank thermistor (temperature sensor) harness going from the tank to the control board. Check for pinched, cut, or burned wires and loose or corroded connectors. Reseat the connector firmly.
• Test the thermistor: Disconnect the thermistor from the board and measure its resistance with a multimeter. Compare the reading to the GE service chart for the approximate water temperature (typically 10–50 kΩ depending on temperature). If it reads open (OL) or 0 Ω, the sensor is defective.
• Check the control board input: If the thermistor tests good, inspect the control board for burn marks or corrosion at the sensor input pins. Lightly clean oxidation and reseat the connector.
• Reset power: Restore power at the breaker and see if the F1 code clears. If the code returns and the sensor and wiring are confirmed good, the control board is likely faulty.
• Replace parts as needed: Replace the tank thermistor if out of spec. If the sensor and wiring are good but F1 persists, replace the electronic control board.

When to call a professional: If you are not comfortable testing resistance or working around 240 V circuits, contact a qualified technician to diagnose and replace the sensor or control board.