Bradford White electronic gas water heater shows E05; unit may short-cycle or not fire.

Safety: Turn off power and gas before removing any covers or sensors. Allow the tank to cool.

Steps:

• Locate the thermistor: On many Bradford White models, the tank temperature sensor is threaded into the tank or mounted in a well near the bottom/front of the heater and connects to the gas control valve via a small harness.
• Inspect wiring: Check the harness for cuts, melted insulation, or loose connectors. Reseat the plug at the gas control valve.
• Test resistance: With power off and wires disconnected, measure the resistance of the thermistor with a multimeter. Compare to Bradford White temperature/resistance chart (e.g., around 10kΩ at room temperature, depending on model). If reading is open, shorted, or far off spec, replace the sensor.
• Replace sensor if needed: Drain water below the sensor level if it threads into the tank. Remove the old sensor, install the new one with appropriate sealant if specified, and reconnect the harness.

If the code persists after sensor replacement and wiring checks, the gas control valve's internal temperature circuit may be defective and require replacement by a professional.