Keep the furnace off. Do not reset a rollout switch. If you smell gas or a carbon-monoxide alarm sounds, leave the building and contact emergency services or the gas utility.
What does Miller code 6 Blinks mean?
Miller furnace code 6 Blinks means the flame-rollout switch is open on the supported control family. Confirm the model number and diagnostic chart inside the furnace door before replacing parts.
What causes Miller code 6 Blinks?
- A blocked flue or combustion-air path
- A burner or gas-pressure problem
- A damaged or restricted heat exchanger
Can I troubleshoot Miller code 6 Blinks?
Keep the furnace off. Do not reset a rollout switch. If you smell gas or a carbon-monoxide alarm sounds, leave the building and contact emergency services or the gas utility.
How much does Miller code 6 Blinks cost to fix?
A heat exchanger replacement typically costs between $500 and $3,500 nationally.
When should I call a technician?
Leave the furnace off and call a licensed technician for a combustion-safety inspection.
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: Nortek single-stage condensing furnaces using the documented Emerson integrated control.
- Nortek Global HVAC: Single Stage Condensing Gas Furnaces — Installation Instructions
1041594D · Nortek single-stage condensing gas furnaces using the documented Emerson integrated control; manufactured-home models and older boards 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.