Dishwasher shows E20 and may not start or may stop with no other obvious symptom; used on some SMEG platforms for generic motor/triac faults.

Safety first: Unplug the dishwasher before any electrical testing.

• Check for obvious shorts: Inspect the circulation and drain pumps for burnt smell, melted plastic, or water ingress.
• Measure motor resistance: With a multimeter, check the resistance of the circulation and drain pump windings. Very low resistance or a direct short to earth indicates a failed motor.
• Inspect wiring harness: Look for chafed wires where the harness passes over metal edges or moves with the door.
• Control board inspection: Remove the control board and inspect the motor triacs for burn marks or cracking. Board-level repair or replacement is usually required.
• Professional service recommended: Because this involves mains-level power electronics, have a qualified technician perform final diagnosis and repair.