Goodman Furnace 1-Flash Error Code — What It Means
A 1-flash code on a Goodman furnace indicates an ignition failure or flame failure condition. This means the furnace attempted to light the burners but could not establish or prove a stable flame within the allowed retry cycles, so the control board locked out and posted the fault. The fault typically appears after the inducer runs, the pressure switch closes, and the igniter glows, but no flame is detected or the flame is lost immediately after ignition.
Common Causes
- Dirty or failed flame sensor Oxidation, soot, or contamination on the flame sensor rod prevents the control board from reading the flame signal, causing the board to shut off the gas valve even when flame is present.
- Weak or cracked hot surface igniter An igniter that does not glow hot enough or has cracks will fail to light the gas reliably during the ignition trial.
- No gas supply or interrupted gas flow The manual gas shutoff valve may be closed, the supply line may be interrupted, or the gas valve itself may not be opening when energized by the control board.
- Dirty burners or restricted crossover ports Rust, debris, or blocked burner ports prevent proper flame carryover from the first burner to the rest of the burner rack, causing uneven or failed ignition.
- Low gas supply pressure Insufficient gas pressure at the furnace inlet can cause weak or delayed ignition, leading to flame-proving failure.
- Failed gas valve coil or control board output A defective gas valve that does not open when commanded, or a control board that does not send voltage to the valve, will prevent gas flow to the burners.
Step-by-Step Fix
- Confirm the model number and verify the fault code against the control board label or Goodman’s model-specific diagnostic chart, since code meanings can vary by product family.
- Check the gas supply by confirming the manual shutoff valve is open, the gas meter or LP tank has adequate fuel, and the gas valve is receiving voltage during the ignition trial.
- Inspect the hot surface igniter for cracks, contamination, or weak glow. Test for continuity with a multimeter if the furnace is off. Replace the igniter if it is damaged or does not glow bright orange during startup.
- Remove and clean the flame sensor rod with fine-grit sandpaper or a non-abrasive pad to remove oxidation and soot. Inspect the sensor mounting and wiring for looseness or corrosion.
- Inspect the burners and crossover passages for rust, debris, or blocked ports. Remove the burner assembly if necessary and clean or replace corroded or obstructed components.
- Check all wiring connections to the igniter, gas valve, flame sensor, and control board for loose, damaged, or heat-damaged terminals. Repair or replace faulty connectors.
- Cycle the furnace through at least three ignition attempts after repairs to confirm stable ignition, proper flame carryover, and reliable flame-proving signal retention.
Parts Often Needed
| Part | Notes |
|---|---|
| Goodman hot surface igniter | Amazon | Match the igniter style and mounting to your exact furnace model. Silicon nitride igniters are common on newer Goodman units. |
| Goodman flame sensor | Amazon | OEM sensor rod and mounting bracket specific to your furnace model. Verify mounting clip and length before ordering. |
| Goodman gas valve | Amazon | Requires exact model cross-reference. Confirm voltage rating and coil configuration match your control board output. |
| Goodman burner assembly | Amazon | Order only if burners are corroded, cracked, or crossover ports cannot be restored by cleaning. |
When to Call a Pro
Call a licensed HVAC technician if you are not comfortable working with gas appliances, if you cannot verify proper gas pressure or valve operation, or if the furnace continues to post a 1-flash code after cleaning the flame sensor and inspecting the igniter. A technician will use a combustion analyzer to verify gas pressure, measure flame-sense microamperage, and test control board outputs safely. If the control board or gas valve must be replaced, professional diagnosis ensures the correct part and prevents misdiagnosis that can damage other components.