Goodman GMVM970803BN Error Code E4: Flame Detected When No Flame Should Be Present

What Does Code E4 Mean?

An E4 code on the Goodman GMVM970803BN indicates the flame sensor is reporting a flame signal at a time when no flame should exist — either before the gas valve has been commanded open or after it should have closed. This is a critical safety condition because it suggests either an actual uncontrolled flame in the burner area or an electrical fault generating a false flame signal. The Integrated Control Module responds by running both the VFD-controlled inducer and the circulator blower continuously to purge the area, while refusing to allow any new ignition attempt.

Unlike the E6 low-flame-signal warning on this board — where the sensor sees too little flame while the furnace runs normally — E4 is the opposite and more urgent case: the sensor sees flame it should not. And unlike an E0 lockout, which follows three failed attempts to light, E4 can appear when the board detects flame outside the expected window entirely. This furnace relies on flame rectification, a very sensitive microamp circuit, so it is quick to flag any unexpected flame signal.

The most likely cause is a short circuit in the flame sensor wiring or the sensor rod grounding against the burner assembly, which creates a false current path that mimics flame detection. A gas valve that closes too slowly, letting gas flow briefly after it should be shut, can also produce a lingering burner flame that the sensor legitimately detects. In rare cases residual combustion heat right after shutdown can cause a momentary false reading.

Because E4 involves both the gas system and the flame-detection safety circuit, it is entirely a professional service issue — there is no safe homeowner step for a flame-when-none-should-exist condition on this furnace.

What You'll Notice

• Both the inducer and the circulator blower run continuously while the furnace makes no heat
• The control module displays E4 and a ComfortNet thermostat shows "Call for Service" / "Check Furnace"
• The furnace will not attempt a new ignition cycle even when the thermostat calls for heat
• The behavior may follow the burner not shutting off cleanly, or appear right after a normal shutdown
• In serious cases you may notice signs of a flame lingering in the burner area after the cycle should have ended

Common Causes

How This Is Diagnosed

A technician treats E4 as a flame-sense-versus-gas-valve timing conflict and separates a false electrical signal from a real lingering flame. With power off, they inspect the flame sensor rod and its lead for a short to ground, damaged insulation, or the rod contacting the burner assembly, since a stray current path makes the board see flame that is not there. They also verify the sensor is mounted and routed correctly.

If the sensing circuit is sound, the technician checks whether flame is actually persisting: they confirm the gas valve closes promptly and fully when de-energized and look for a slow-closing valve or seepage that leaves a small flame after shutdown. Depending on the finding, the flame sensor, its wiring, or the gas valve is repaired or replaced — all professional work on the gas and safety circuits.

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 display shows E4 and both blowers run nonstop with no heat
• The furnace refuses to start a new heating cycle after the code appears
• You see or suspect a flame remaining in the burner area after the furnace should have shut off
• The code appears right after the burners fail to extinguish cleanly at the end of a cycle
• You smell gas at any time — leave the house immediately and call your gas company

✓ Verified against manufacturer service manual — March 2026