Dryer displays E20 and may not start; sometimes accompanied by interior light not working

Safety first: Disconnect power before working on the door switch or light socket.

Step-by-step checks:

• Check drum light: Replace the drum light bulb with a known good bulb of the correct type. If the new bulb immediately fails or flickers, suspect a socket or wiring issue.
• Inspect light socket: Look for signs of arcing, heat damage, or corrosion. Replace the socket if damaged.
• Door switch test: Access and test the door switch for proper operation with a multimeter. Replace if intermittent or open when the door is closed.
• Wiring inspection: Trace the wiring between the door switch, light socket, and control board. Repair any damaged insulation or loose connections.

When to call a technician: If E20 persists after replacing obvious failed parts, the control board may be involved and should be checked by a professional.