Your Goodman furnace starts its cycle — the inducer runs, you can hear it — but the burners never light. Or the ignitor glows but the flame doesn't establish. This is one of the most common furnace service calls in Minnesota, and many cases can be resolved without a technician. Here's the systematic diagnostic approach.
Understanding the Ignition Sequence
Before diagnosing, understand what should happen when your Goodman furnace starts:
- Thermostat sends heat call to control board
- Draft inducer motor starts (creates negative pressure)
- Pressure switch closes (confirms inducer is working)
- Control board waits for warm-up (15–30 seconds)
- Hot surface ignitor energizes (glows orange-red, 1100–1400°F)
- Gas valve opens (burners receive gas)
- Flame establishes within 4–7 seconds
- Flame sensor detects flame (if no flame detected, gas valve closes, retry cycle begins)
- Blower motor starts after warm-up delay
Failure can occur at any step. The LED error codes tell you where.
Step 1: Read the Error Codes
Look at the small LED light on the Goodman control board (visible through the furnace inspection window). Count the flashes:
| Flash Pattern | Meaning | Start Here |
|---|---|---|
| 2 flashes | Pressure switch stuck open | Check condensate drain, vent pipes, inducer |
| 3 flashes | Pressure switch stuck closed | Check pressure switch hose for obstruction |
| 4 flashes | High limit switch open | Check filter, verify airflow |
| 6 flashes | Ignition failure / no flame | Check ignitor, flame sensor, gas supply |
| 7 flashes | Flame sensed without gas call | Check for gas valve issues |
| Continuous | Normal operation | — |
For 6-flash (ignition failure), continue with the steps below. See the full Goodman error code guide for all patterns.
Most Common Causes of No-Ignite
1. Cracked or Failed Hot Surface Ignitor
The hot surface ignitor (HSI) is the most commonly replaced ignition component. It's a silicon nitride or silicon carbide rod that glows to ignite the gas. Over time (typically 5–7 years), it becomes brittle and cracks — either completely (no glow at all) or partially (glows but at lower temperature, insufficient to ignite gas).
How to check: With furnace in a startup cycle, watch through the inspection window. Does the ignitor glow orange-red? If no glow, the ignitor has likely failed. If it glows dimly or weakly, it may be partially cracked.
Fix: Replace the hot surface ignitor. Part cost: $20–$40. Readily available at HVAC supply houses and online. Straightforward DIY repair — turn off power and gas, disconnect wires, unscrew mounting bracket, swap ignitor, reassemble. Handle new ignitor with gloves — skin oils can cause premature failure.
2. Dirty Flame Sensor (Most Common Cause of Repeated Short Cycles)
The flame sensor is a metal rod that sits in the burner flame and passes a small current through the flame to verify it's burning. Over time, the sensor becomes coated with oxidation, reducing its ability to detect flame. The furnace lights, burns for 2–5 seconds, then shuts off — often repeating 3 times before locking out.
How to check: If the furnace lights briefly (you see a flame) then shuts off, dirty flame sensor is the most likely cause.
Fix: Clean the flame sensor. Turn off power and gas. Remove the sensor (one screw, one wire). Lightly sand the metal rod with fine (400-grit) emery cloth — not sandpaper, not steel wool. Reinstall. This resolves the issue in most cases. If cleaning doesn't help, replace the sensor ($15–$30).
3. No Gas Supply
Check:
- Is the manual gas shutoff valve near the furnace open (handle parallel to pipe = open, perpendicular = closed)?
- Is gas service active? Test another gas appliance (stove, water heater)
- Did you recently have gas work done? The system may need to be bled of air
4. Failed Gas Valve
If the ignitor glows, gas should flow — if the gas valve doesn't open, no gas reaches the burner. Gas valve failure is less common but possible, especially on older furnaces. A technician can test gas valve operation directly. Replacement cost: $200–$400 parts + labor.
5. Control Board Failure
If no error codes display and the furnace doesn't respond to thermostat calls at all, the control board may have failed. Control boards can be damaged by power surges or voltage spikes. Replacement: $150–$400 for the board itself.
When to Call a Technician
- Gas smell anywhere near the furnace (leave home, call gas company)
- Error code points to gas valve or control board failure
- Ignitor and flame sensor replaced but still no ignition
- Multiple rapid lockouts (safety lockout after 3 failed attempts)
Preventing Ignition Failures
- Annual tune-up includes flame sensor cleaning
- Keep filters clean — clogged filters can trigger high-limit shutdowns that reset, creating confusing symptoms
- If furnace is 10+ years old and ignitor has never been replaced, consider replacing proactively before failure
Related Resources
- Goodman Error Codes: Full Diagnostic Guide
- Furnace Not Turning On: Diagnostic Checklist
- Furnace Pressure Switch Guide
- Furnace Flame Color: What It Means
- Minnesota Furnace Emergency: What to Do
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