Furnace will not start; control board shows E01 and inducer motor does not run

Safety first: Turn off power to the furnace at the service switch or breaker and shut off gas before removing panels. Do not bypass safety switches for operation.

• Check venting: Go outside and inspect the PVC intake and exhaust pipes used on Napoleon high-efficiency furnaces. Remove any snow, leaves, bird nests, or debris. Make sure the pipe terminations are not iced over.
• Inspect pressure tubing: Remove the front panel, locate the round pressure switch mounted near the inducer assembly. Inspect the rubber or silicone tubing from the pressure switch to the inducer housing or collector box. Ensure it is not cracked, kinked, or filled with water. Re-seat both ends firmly.
• Test the pressure switch: With power off, disconnect the wires and check continuity across the pressure switch terminals while gently applying suction to the tubing port. The switch should close (show continuity). If it does not, the pressure switch may be defective.
• Check inducer operation: Restore power briefly and call for heat at the thermostat. Confirm the inducer motor starts. If the inducer does not run or is very weak, the control board may not be able to pull the pressure switch closed.
• When to replace: If venting is clear, tubing is intact, and the inducer runs normally but E01 persists and the pressure switch does not close, replace the pressure switch with the correct Napoleon-rated part number for your model.