No ignition, furnace does not light, status LED shows code 11 (no previous code stored).

Safety first: Turn off power to the furnace at the service switch or breaker before removing panels. Do not bypass any safety switches.

This code usually means the control has been powered up and no active fault is stored.

• Check thermostat call: Set thermostat to HEAT and raise the setpoint 5°F above room temperature. Verify the thermostat display is on and calling for heat.
• Inspect low-voltage wiring: Remove the blower door and locate the control board. Check R, C, W wires for tight connections. Look for any broken or chewed thermostat wires at the furnace and near the thermostat.
• Check 3–5A low-voltage fuse: On many Carrier boards there is an automotive-style blade fuse. With power off, pull and visually inspect it. Replace with the same rating if blown.
• Restore power and test: Turn power back on, close the blower door (door switch must be engaged), and call for heat again. Observe if a new code appears when the furnace attempts to start.

If the furnace still does not respond and no new code appears, the control board or thermostat circuit may be faulty and should be diagnosed by a qualified technician.