Quick Answer
Okay, here's the quick version. Your furnace ignitor isn't glowing and you've got no heat. Nine times outta ten, that little part has just burnt out. They're like lightbulbs, they don't last forever, especially the older silicon carbide (HSI) ones, or even newer nitride ignitors can fail. You can probably swap it yourself if you're handy; the part's maybe $30-150 depending on the model. Or you can call a guy like me, and you're looking at probably $250-$600 all said and done. It's the most common furnace ignition component failure I see every single winter.
Common Symptoms
Possible Causes
Step-by-Step Diagnosis
Step 1
Shut off power to the furnace at the circuit breaker. This is a critical safety step.
Step 2
Remove the furnace access panel to expose the burner assembly.
Step 3
Locate the ignitor. It's a small element on a ceramic base, usually near the first burner.
Step 4
Visually inspect the ignitor with a flashlight for any visible cracks or white burn spots. If you see one, that's your problem.
Step 5
Check the wire plug connected to the ignitor. Make sure it's pushed in securely and isn't corroded or melted.
Step 6
(Advanced) If it looks okay, use a multimeter set to Ohms to test for continuity. An 'OL' reading means it's broken internally.
DIY vs Professional Costs
| Repair Type | DIY Cost | Professional Cost | Time Required |
|---|---|---|---|
Cleaning a Dirty Ignitor | $0 - $10 | N/A | 30 minutes |
Replacing a Faulty Ignitor | $30 - $150 | $250 - $600 | 30-60 minutes |
Control Board Replacement | $150 - $600 (Part Only) | $600 - $1200+ | 1-2 hours |
When to Call a Professional Hvac
- If you smell gas at any point. Stop, leave the house, and call your gas company and a professional immediately.
- If you've replaced the ignitor yourself and the furnace still won't light. This means the problem is elsewhere, likely the control board or a safety switch.
- If you are not 100% confident in your ability to work safely with 120-volt electricity.
- If you suspect the issue is the main control board, as a mistake during replacement can be very costly.
Prevention Tips
- Change your furnace filter religiously every 1-3 months. A dirty filter is the #1 cause of premature part failure.
- Schedule an annual professional tune-up. A tech can spot a weak ignitor before it fails completely and leaves you cold.
- Keep the area around your furnace clear of clutter and debris to ensure it has plenty of fresh air for combustion.
- When replacing an old black ignitor, ask for a silicon nitride (grey) upgrade kit. They are far more durable and last much longer.
Frequently Asked Questions
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