Turn the furnace off and do not reset it. If you smell gas, leave the building without operating switches and contact the gas utility or emergency services from outside.
What does Intertherm code 5 Blinks mean?
Intertherm furnace code 5 Blinks means flame was sensed for more than four seconds while the gas valve was off on the supported control family. Confirm the model number and diagnostic chart inside the furnace door before replacing parts.
What causes Intertherm code 5 Blinks?
- A gas valve leaking or stuck open
- A shorted flame-sensing circuit
- A failed integrated control board
Can I troubleshoot Intertherm code 5 Blinks?
Turn the furnace off and do not reset it. If you smell gas, leave the building without operating switches and contact the gas utility or emergency services from outside.
How much does Intertherm code 5 Blinks cost to fix?
A gas valve replacement typically costs between $300 and $1,000 nationally.
When should I call a technician?
Turn the furnace off and call a licensed technician immediately to test the gas valve and flame-proving circuit.
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.