Smell Gas Near Your Furnace? Do This Now (Not Troubleshooting)
This is the one page on our site with no checklist and no troubleshooter. If you smell gas — the rotten-egg smell that's added to natural gas and propane on purpose — the answer is not to investigate. It's to leave.
Do this, in this order
- Don't flip any switches. Not lights, not the furnace switch, not the garage door opener. A switch can spark.
- Don't use a phone inside. Don't start the car in an attached garage.
- Leave the house. Everyone, including pets. Leave the door open behind you if you can do it on the way out.
- From outside, call your gas company's emergency line (it's on your bill, or call 911). They come out free, day or night, and they don't need you to have "confirmed" anything.
- Don't go back in until they say it's safe.
That's it. There's no step where you check the furnace.
What is NOT a gas smell
Not everything that smells bad is gas. Two common false alarms:
- Burning dust, the first heat of the season. A dusty, hot smell for the first 15–30 minutes when the furnace first runs in fall. It fades. If it smells electrical or plastic, or it doesn't fade, that's a different problem — see burning smell when the heat comes on.
- Sewer or drain smell. Rotten-egg can also be a dry drain trap letting sewer gas in — often near a basement floor drain or an unused sink. If the smell is strongest at a drain and nowhere near gas appliances, pour a pitcher of water down the drain and see if it clears over a day.
When in doubt, treat it as gas. The gas company would rather come out for a dry drain trap than not come out for a leak.
After the gas company clears you
If they found and fixed a leak at the furnace, you'll want a technician to check the furnace before you run it. If they found nothing and the furnace still won't heat, now the normal troubleshooting applies — start at furnace won't turn on.
Related pages
Start the free troubleshooter → — only after the gas company has cleared the house. Free. No sign-up. Don't pay $150 to flip a switch.
Start the free troubleshooter →Free · no sign-up · no personal info · about ten minutes