Control board shows E0, furnace will not start any heating cycle

Safety first: Turn OFF power to the furnace at the service switch and breaker. Verify power is off with a non-contact voltage tester before touching any wiring.

• Step 1 – Inspect low-voltage wiring: Remove the blower door to access the Ducane IFC board. Check the R, C, W, Y, and G thermostat wires for loose connections, corrosion, or broken conductors. Tighten any loose terminal screws.
• Step 2 – Check the 3–5A blade or automotive-style fuse on the board: If the fuse is blown, inspect for shorts in thermostat wiring (especially where it passes through sheet metal). Replace the fuse with the same rating only after correcting any short.
• Step 3 – Confirm line voltage polarity and ground: Verify hot and neutral are correctly landed on the L1 and neutral terminals and that the ground wire is secure to the furnace chassis.
• Step 4 – Power cycle: Restore power and see if E0 clears. If the code returns immediately and wiring and fuse are good, the IFC board may be defective.
• Step 5 – When to call a pro: If you suspect a failed control board or incorrect supply wiring, contact a qualified HVAC technician. Board replacement and line-voltage diagnostics should be done by a professional.