Controller displays E20 and prevents start, often after maintenance

Safety first: Ensure the generator cannot auto-start while doors are open. Disable auto mode.

• Inspect door switches: Locate the safety interlock switches on access doors or panels. Ensure doors close fully and actuate the switch plungers or magnets.
• Check alignment: Adjust door latches or switch mounting so that the switch is fully engaged when the door is closed.
• Inspect wiring: Check the interlock wiring harness for cuts, loose connectors, or corrosion. Repair as needed.
• Test continuity: With the door closed, use a multimeter to verify that the interlock circuit closes properly. Replace a defective switch.
• Do not bypass permanently: While temporary bypass may be used for diagnostics by qualified personnel, the interlock must be restored for safe operation.