What does Heil code 10 Flash mean?
Heil furnace code 10 Flash means the furnace detected reversed line polarity, or incorrect transformer phasing on twinned units on the supported control family. Confirm the model number and diagnostic chart inside the furnace door before replacing parts.
What causes Heil code 10 Flash?
- Reversed line and neutral wiring
- A missing or poor equipment ground
- Incorrect transformer phasing on twinned furnaces
Can I troubleshoot Heil code 10 Flash?
- Turn the furnace off at its service switch.
- Do not alter line-voltage wiring or grounding connections yourself.
How much does Heil code 10 Flash cost to fix?
A control board replacement typically costs between $150 and $500 nationally.
When should I call a technician?
Call a licensed technician or electrician to verify polarity, grounding, and supply voltage.
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: ICP control boards covered by document 44001202103 and using its 2–10 flash table.
- International Comfort Products: Furnace Control Board Diagnostic Codes
44001202103 · ICP furnace control boards covered by document 44001202103; confirm the control-board label and door chart.
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.