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Furnace Blinking Green Light

A green LED on your furnace usually indicates normal operation or standby mode — but flash patterns can still signal faults on some brands. Select your brand below to confirm what your specific light means.

Reviewed July 2026

What does furnace blinking green light mean?

Green often means the control board has power and the unit is idle or running normally. On some models, green flashes still encode error codes. Always cross-check your brand's diagnostic guide — color alone isn't enough to diagnose a problem.

What usually causes furnace blinking green light?

Normal standby (no fault)most common

Typical repair: $20–$75

Communication or board status codecommon

Typical repair: $300–$800

Ignition sequence in progresspossible

Typical repair: $150–$400

Find your exact error code

Select your furnace brand to jump to the code page for this symptom.

Goodman1 FlashIgnition or flame-proving failureCarrier14Ignition lockoutLennox200Rollout circuit hard lockoutRheem10One-hour ignition lockoutYork1 BlinkFlame detected when the gas valve should be off

What should I check first when furnace blinking green light?

  1. Note whether the green light is steady or blinking.
  2. If blinking, count flashes and match your brand below.
  3. Confirm the thermostat is calling for heat if the unit won't start.
  4. See your brand's code list if heat isn't working despite a green light.

What a repair costs

A furnace filter replacement typically costs between $20 and $75 nationally.

Typical repair cost
$20 – $75furnace filter replacement
Where the money goes
Part $10–$50Labor $0–$65Typical labor time: 0.25 hrs

This is general information, not professional advice. Gas, electrical, and combustion repairs can be dangerous — when in doubt, call a licensed technician.