Indoor unit will not start; display shows E01 shortly after power-on.

Safety first: Turn off the breaker to the Toshiba air conditioner and verify power is off before removing any covers.

• Step 1 – Power reset: Turn the unit off at the remote, then switch off the dedicated breaker for 5 minutes. Restore power and test. If E01 returns, continue.
• Step 2 – Inspect indoor–outdoor cable: Remove the indoor front panel and control cover. Locate the multi-core communication/power cable going to the outdoor unit. Check for burnt insulation, cuts, or signs of rodents. Tighten all terminal screws.
• Step 3 – Check connectors on indoor PCB: Gently press all low-voltage connectors into the indoor main PCB. Look for corrosion or discoloration. Reseat any loose plugs.
• Step 4 – Check outdoor terminal block: At the outdoor unit (power off), remove the electrical cover. Verify the L, N, and communication terminals match the indoor wiring order and are firmly tightened.
• Step 5 – Test continuity: With a multimeter, test continuity of each conductor in the interconnecting cable from indoor to outdoor. Replace the cable if any conductor is open or shorted.
• Step 6 – PCB diagnosis: If wiring is correct and intact but E01 persists, the indoor control PCB or outdoor control PCB may be defective. At this point, professional diagnosis with Toshiba service tools is recommended.