Washer-dryer combo will not start any cycle; display shows F01 and may beep repeatedly.

Safety first: Unplug the washer-dryer combo or switch off the dedicated circuit breaker before any inspection. Do not work on live circuits.

Step-by-step checks:

• Power reset: Disconnect power for 5–10 minutes to discharge the control board. Restore power and try a short cycle. Sometimes transient faults clear after a hard reset.
• Check outlet and supply: Verify the wall outlet has 120V AC (North America) using a meter or by plugging in another appliance. Confirm the unit’s power cord is fully seated and not damaged.
• Inspect wiring to CCU: Remove the top panel (usually rear screws, then slide back). Locate the main control board (CCU) at the rear or side. Check all harness connectors for being fully seated, no corrosion, and no burnt pins. Reseat each connector one at a time.
• Look for board damage: Examine the CCU for burnt spots, bulging capacitors, or melted areas. Any visible damage usually means the board must be replaced.
• Test line filter and incoming power: Trace the power from the line filter/noise filter to the CCU. Ensure connectors are tight and there is no sign of overheating.

When to replace: If F01 returns immediately after reset and wiring is intact, the main control board is likely defective and should be replaced with the correct Whirlpool OEM part. Replacement involves transferring connectors one-by-one to the new board, mounting it securely, and reassembling the cabinet.