Goodman GMVM970803BN Error Code E0: Lockout

What Does Code E0 Mean?

During each heating call, the GMVM970803BN's Integrated Control Module runs a strict sequence: it spins up the VFD-controlled inducer, confirms the pressure switch has closed, energizes the hot surface igniter, then opens the modulating gas valve and looks for the microamp flame-sense signal. E0 appears after three attempts in a single call for heat either fail to establish flame or lose flame shortly after it lights. The board then stops trying, displays E0, and a ComfortNet thermostat shows "Call for Service" and scrolls "Check Furnace."

E0 is the escalation endpoint for several individual faults this board can flag. Common reasons for the repeated failures include a dirty or cracked hot surface igniter that never reaches temperature, a flame sensor coated with oxidation that cannot report the flame, or an interrupted gas supply such as a closed manual shutoff. It can also chain off a venting problem: if the low-stage pressure switch will not close (the E2 condition — switch stuck open after the inducer runs) or is already closed before the cycle (the E1 condition — switch stuck closed at start), ignition never proceeds cleanly, and repeated recycles roll up into an E0 lockout.

Because this furnace modulates, a weak or lazy burner flame from low gas pressure, a partially restricted flue, or an underperforming induced-draft blower can also cause the board to lose flame mid-cycle and count another failed attempt. A preceding E6 low-flame-signal warning often explains why the unit finally reached E0. Each of those is a professional diagnosis, not a homeowner adjustment.

The lockout is self-clearing: the board automatically retries after roughly one hour, and you can force a retry by cutting furnace power briefly or lowering then raising the thermostat. But those only restart the sequence — they do not repair the igniter, sensor, gas, or venting issue that caused the three failures, so a recurring E0 needs a technician.

What You'll Notice

• The control module displays E0 and the furnace produces no heat until it retries or is reset
• You may hear the inducer and igniter run through several attempts before everything stops
• The house goes cold and a ComfortNet thermostat shows "Call for Service" and "Check Furnace"
• The furnace appears to start on its own about an hour later, then may lock out again
• Flame may light briefly and then drop out, or never light at all, on each attempt

Common Causes

How This Is Diagnosed

A technician reads E0 as "three failed ignitions" and works the ignition sequence in order. They first confirm gas is actually reaching the furnace (manual shutoff open, supply pressure correct), then inspect the hot surface igniter for cracks and proper glow and check the flame sensor for oxidation and correct position in the flame. They also review the fault history stored on the module, because a preceding E1, E2, or E6 points to whether the failure was upstream in venting or flame sensing.

If ignition components look good, the technician moves to flame stability: manifold gas pressure, flue and intake for restriction, and induced-draft blower performance, since a lazy flame or weak draft makes the board lose flame after it lights. The goal is to find the single root cause behind the three recycles rather than just resetting the lockout.

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:

• E0 returns after the furnace resets itself or after you cycle power
• The burner lights and then drops out repeatedly before the lockout
• An E1, E2, E6, or igniter-related code appeared shortly before the E0
• You confirmed the gas is on and the filter is clean but the lockout persists
• You smell gas at any point — leave the house immediately and call your gas company

✓ Verified against manufacturer service manual — March 2026