What does Coleman code 12 Blinks mean?
Coleman furnace code 12 Blinks means the igniter circuit is open on the supported control family. Confirm the model number and diagnostic chart inside the furnace door before replacing parts.
What causes Coleman code 12 Blinks?
- A cracked or open hot-surface igniter
- Loose or damaged igniter wiring
- A failed igniter relay on the control board
Can I troubleshoot Coleman code 12 Blinks?
- Turn power off and look through the burner-viewing area for an obviously cracked igniter without touching it.
- Restore power once and observe whether the igniter glows; do not continue resetting the furnace.
How much does Coleman code 12 Blinks cost to fix?
A furnace ignitor replacement typically costs between $150 and $500 nationally.
When should I call a technician?
Call a technician if the igniter does not glow or the fault returns.
Sources and model scope
Fault codes vary by model and control board. Confirm the diagnostic chart inside your furnace panel or the official manual before acting.
Scope used here: Johnson Controls integrated furnace controls using the documented 1–12 red-flash table.
- Johnson Controls Unitary Products: Gas Furnace Installation Manual
272441-UIM-E-0513 · Johnson Controls integrated furnace controls with the 1–12 red-flash table in this manual; other model families may differ.
Compiled by Warmlo Editorial · Reviewed August 2026
This is general information, not professional advice. Gas, electrical, and combustion repairs can be dangerous — when in doubt, call a licensed technician.