Furnace Pilot Light Won't Stay Lit

Common Symptoms

You might be experiencing this problem if you notice any of these signs:

• Pilot light goes out after releasing button
• No flame visible in pilot assembly
• Furnace won't ignite or stay running
• Gas smell when pilot won't light
• Pilot flame is weak or yellow instead of blue
• Pilot stays lit briefly then extinguishes
• Cold air blowing instead of heat
• Thermocouple looks dirty or corroded
• Draft blowing out pilot light

Step-by-Step Diagnosis

Follow these steps to identify the exact cause of your problem:

1. Check if pilot light is completely out
2. Inspect pilot flame color (should be steady blue)
3. Verify gas valve is fully open
4. Check for drafts near furnace
5. Inspect thermocouple position relative to pilot flame
6. Look for dirt or debris in pilot assembly
7. Test if pilot stays lit when button held for 60 seconds
8. Check for soot buildup around pilot area
9. Verify adequate ventilation to furnace
10. Listen for gas flow when lighting pilot
11. Note if pilot goes out immediately or after minutes
12. Check for recent power outages or gas supply interruptions

Most Common Causes (Ranked by Likelihood)

DIY Solutions

Step-by-Step Instructions:

1. Turn gas valve to OFF and wait 5 minutes for gas to dissipate
2. Turn gas valve to PILOT position
3. Hold reset/pilot button down firmly
4. Light pilot with long lighter while holding button
5. Keep button pressed for 60 seconds after pilot lights
6. Slowly release button - pilot should stay lit
7. If pilot goes out, wait 5 minutes and repeat
8. Clean pilot orifice with compressed air or fine wire
9. Adjust thermocouple to be in blue part of pilot flame
10. Check thermocouple connection is tight
11. Remove dust and debris from pilot assembly area
12. Verify no drafts from nearby doors or windows
13. If pilot stays lit, turn gas valve to ON
14. Set thermostat to call for heat and verify furnace starts

When to Call a Professional

Don't attempt DIY repairs if you experience any of these situations:

• Strong gas odor that persists
• Pilot won't light after multiple attempts
• Yellow or flickering pilot flame
• Thermocouple replacement needed and you're not comfortable
• Gas valve appears damaged or stuck
• Furnace is older than 20 years (consider replacement)
• Soot buildup around burners or pilot
• Carbon monoxide alarm triggered
• Pilot goes out immediately after releasing button
• Recent gas line work or pressure changes

Prevention Tips

Stop this problem before it starts with these preventive measures:

• Schedule annual furnace inspection and cleaning
• Clean pilot assembly during yearly maintenance
• Replace thermocouple every 3-5 years preventatively
• Ensure proper ventilation in furnace area
• Keep furnace area draft-free
• Install carbon monoxide detectors on every floor
• Address soot buildup immediately
• Don't block furnace intake or exhaust vents
• Test pilot light monthly during heating season
• Keep furnace room door closed if drafty