Furnace lights up then immediately goes out
Even after replacing the igniter, gas valve, and flame sensor, a furnace can fail to stay lit if the new igniter isn't drawing the correct amount of electrical current. This prevents the control board from sensing proper operation and keeping the gas valve open, stopping the system from completing its heating cycle.
What the numbers show
Counted from the threads quoted below. How we count
- This comes up 52.2× more often in r/appliancerepair than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Replacing multiple parts sequentially
- 2Checking incoming gas pressure and flame signal
- 3Consulting forums for diagnostic steps
- 4Consulting AI tools like Google Gemini for troubleshooting advice
- 5Checking the amp draw of the ignitor
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“I replaced the gas valve and the igniter and flame sensor on this furnace, did I get a bad gas valve possibly? Old one Was doing the same thing. Any advice would be nice. I’m just a new tech trying to figure it out.”source ↗
“Google gemini says I need to replace the igniter, can anyone confirm?”source ↗
“What’s the amp draw of the ignitor? I’ve never seen an ignitor cause a valve to act like this and I don’t hear the valve closing and opening.”source ↗
“100% new igniter. Not drawing enough amps to keep the valve open.”source ↗
“Yep looks like you need a new ignitor to me.”source ↗
Where this came up
People with this problem also raised
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- 3Why does my thermostat keep losing power and resetting?
- 2Oven igniter glows bright orange but gas won't turn on