Goodman furnace E0: Lockout after too many failed ignition attempts

E0 means the furnace made its allowed ignition attempts, none produced a proven flame, and it has stopped trying. It is the display-code equivalent of the one-flash lockout on older boards.

Applies to: Goodman GMVC96, GMVM97, GCVC96, GCVM97 and Amana AMVC96, AMVM97 series gas furnaces with a two-character alphanumeric display. Earlier furnaces with a single flashing LED report the same condition as one flash.

What it means

The control allows a fixed number of ignition attempts, normally three, and counts each one that ends without a proven flame. When the count is exhausted it stops opening the gas valve and shows E0. The furnace is not failing to light at the moment you read the code — it failed repeatedly a while ago and removed itself from service. Most controls clear the lockout automatically after about an hour and try the whole sequence again, which is why a furnace showing E0 often produces one apparently successful cycle and then quits again. That is a retry on a timer, not a recovery. Underneath it, the cause is nearly always no gas at the burners, no ignition source, or a flame that lit and was never detected.

Most common causes

The gas supply is off or interrupted — a closed manual valve, an empty propane tank, or a utility outage.
The hot surface igniter has cracked or failed, so nothing lights the gas.
The flame sensor is coated with oxide, so the burners light and the control cannot see the flame and closes the valve.
The flame sensor has been knocked out of the flame path, with the same effect.
The gas valve is not opening, or manifold pressure is too low for a stable flame.
Poor furnace grounding, which prevents the flame rectification signal being read.
A restricted flue, limiting combustion enough that the flame will not stabilise.

How to diagnose it

Check whether other gas appliances in the house work. If none do, the problem is the gas supply rather than the furnace.
Check the furnace's own shutoff valve is open, and on propane that the tank has fuel.
Watch a full cycle through the sight glass with the panel in place. Whether the burners light at all is the key split — lighting then going out after a few seconds points at flame sensing, never lighting points at gas or ignition.
Note whether the furnace runs once after about an hour and then locks out again. That pattern confirms the automatic retry and tells you the fault is consistent.
Check the display again after a reset rather than assuming; the stored code may differ from the active one.

How to fix it

Restore the gas supply if that is the cause.
Replace the air filter and open closed registers. Neither causes E0 directly, but both accompany enough related faults to be worth eliminating.
Everything else here is licensed work. Cleaning a flame sensor, replacing an igniter, and testing manifold pressure all sit in the flame-sensing circuit or the gas train.
Do not reset repeatedly to force a run. Each reset sends gas to a burner that may not light it, and repeated unburned gas cycles are what the lockout exists to prevent.

Notes

A furnace that lights, burns for a few seconds, then shuts down and eventually shows E0 is the classic dirty flame sensor. It is among the most common causes and one of the cheapest repairs, but it sits in the flame-sensing circuit and is a technician's job.

Sources

This site is a reference, not a substitute for a licensed HVAC technician. Gas appliances can leak carbon monoxide and cause fire. Anything involving gas lines, the heat exchanger, or the flame sensing circuit should be handled by a licensed professional. Pages are written with AI assistance from the sources listed on each page and checked against them before publishing.