Goodman GMVM970803BN Error Code E6: Low Flame Signal

What Does Code E6 Mean?

An E6 code on the Goodman GMVM970803BN is a warning that the flame sensor is producing a weaker-than-normal signal, measured in microamps. This is one of the few codes on this board that does not stop the furnace — the unit keeps operating and heating normally while E6 is displayed. Its severity is low precisely because it is a heads-up, not a shutdown. But it should not be ignored: it marks a trend, and if the signal keeps falling the control module will eventually be unable to confirm flame at all.

The flame sensor is a metal rod that sits directly in the burner flame and works by flame rectification — the flame conducts a tiny current that tells the board a real flame is present. As the furnace runs over many cycles, the rod slowly builds up oxidation or carbon that electrically insulates it, so the microamp signal it can pass gets weaker. When that signal drops below the board's warning threshold, E6 appears. The signal can also read low if the rod is not positioned deep enough in the flame, or if the flame itself is weak or lazy from low gas manifold pressure or restricted combustion air.

The reason E6 matters is what it leads to. This same board declares an E0 lockout after three failed ignition or flame attempts in a single call for heat, and a flame signal that keeps degrading is exactly what eventually causes the board to miss flame and trip that lockout. In other words, E6 is the early, still-running stage of the same problem that, left alone, can turn into a no-heat E0. Catching it while the furnace is still working lets the fix happen on your schedule instead of during a cold-night shutdown.

What You'll Notice

• The dual 7-segment display shows E6 while the furnace continues to run and heat the home normally
• There is no loss of heat yet — this is an advisory, not a shutdown
• Over time you may notice occasional missed ignitions or brief flame dropouts as the signal weakens further
• The burner flame may look lazy, yellow-tipped, or weaker than a normal crisp blue flame if a poor flame is the cause
• If ignored long enough, the furnace may progress to an E0 lockout and stop producing heat

Common Causes

How This Is Diagnosed

A technician confirms the weak signal by measuring the flame sensor current with a meter that reads microamps while the burners are lit, comparing it against the flame-sense value in the model's specifications. If the reading is low, the usual first step is cleaning the sensor rod — a technician cleans it with a Scotch-Brite pad to remove the insulating oxidation without leaving abrasive residue, taking care not to damage the rod's white porcelain base — and then re-measuring to see the signal recover.

If cleaning does not restore a healthy reading, the technician isolates whether the problem is the sensor or the flame. They verify the rod is positioned so it is fully immersed in the flame, check gas manifold pressure, and inspect the combustion air piping for restrictions, since a lazy or weak burner flame produces a low signal even with a clean sensor. Depending on findings, the fix ranges from a simple cleaning to correcting combustion air or gas pressure, or replacing the sensor.

When to Call a Professional

This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:

• The E6 warning is displayed — schedule service before it can progress to an E0 lockout
• The furnace has begun to occasionally miss ignition or briefly lose flame
• The burner flame looks lazy, yellow, or weaker than a normal blue flame
• E6 keeps returning after service, suggesting a combustion-air or gas-pressure issue rather than just a dirty sensor

✓ Verified against manufacturer service manual — March 2026