Goodman GMSS960803BN Error Code 7 Flashes: Low Flame Signal

What Does Code 7 Flashes Mean?

Seven flashes on the Goodman GMSS960803BN diagnostic LED indicate a low flame signal. The furnace is still operating normally for now, but the flame sensor's microamp reading has dropped below the expected level. This is a warning that the flame detection is degrading and may soon lead to ignition failures.

The flame sensor is a metal rod positioned in the burner flame that conducts a tiny electrical current (typically 1-6 microamps) when immersed in flame. The control board monitors this current to confirm the burners are lit. When the current falls below the normal range but remains above the cutoff threshold, this warning code appears.

If not addressed, the sensor will continue to degrade until the current drops below the minimum threshold. At that point, the furnace will start shutting down during operation and eventually lock out with a 1-flash code. The most common cause is a buildup of oxidation or combustion residue on the sensor rod. The sensor may also be incorrectly positioned in the flame, or low gas pressure may be producing a weak flame.

Common Causes

When to Call a Professional

Contact a licensed HVAC technician if:

• The low flame signal code returns after cleaning the sensor
• The flame sensor rod appears cracked or physically damaged
• The flame appears weak, yellow, or uneven across the burners
• The furnace has started locking out with a 1-flash code
• You suspect low gas pressure (other gas appliances also underperform)

✓ Verified against manufacturer service manual — March 2026