John Wood electronic gas water heater shows E020 and the burner does not light; code appears after long idle period

Safety: Use caution when working around live electrical circuits.

• 1. Measure voltage: With a multimeter, check the voltage at the heater's power input. It should be within the range specified on the rating plate (typically 120 VAC).
• 2. Check outlet and cord: Ensure the plug is fully inserted and the outlet is not loose. Try another known-good outlet if possible.
• 3. Dedicated circuit: Avoid running the heater on a heavily loaded circuit with other large appliances.
• 4. Inspect internal connections: With power off, check internal power wiring and neutral/ground connections for tightness.
• 5. Control board power supply: If line voltage is correct but E020 persists, the board's internal power supply may be failing and the board should be replaced.