On this page
Before you touch anything: the gas-smell rule
If you smell gas, a sustained rotten-egg or sulfur odor near the heater, do not try to relight it and do not flip any switches. Leave the area, get everyone out, and call your gas utility’s emergency line or 911 from outside or a neighbor’s. A relight attempt with gas present is exactly the wrong move. Our gas smell in the house page covers the full leave-first sequence.
A faint whiff right at the burner for a second when you first open the control is different from a lingering smell that fills the space; the latter is the stop signal. When in doubt, treat it as a leak and call. No pilot relight is worth guessing on this.
The safe relight steps
Find the gas control valve at the bottom of the tank. It has a dial with Off, Pilot and On, usually a red or black push-button or a built-in piezo igniter that clicks, and a small viewing window where you can see the pilot flame. Work in this order and do not rush the wait step, because it is what makes the relight safe.
- ·Turn the gas control dial to Off and wait a full five minutes for any unburned gas to clear. Do not skip this.
- ·Turn the dial to Pilot and rotate it so the marker lines up with the pilot position.
- ·Press and hold the control knob (or the separate red button) down to send gas to the pilot.
- ·While holding, click the piezo igniter repeatedly, or hold a long lighter at the pilot tube through the opening, until the pilot flame catches.
- ·Keep holding the knob down 30 to 60 seconds after it lights so the thermocouple heats up, then slowly release.
- ·If the pilot stays lit, turn the dial to On and set your temperature. If it goes out, wait five minutes and try once more.
When it will not stay lit: the thermocouple
If the pilot lights while you hold the knob but dies the moment you let go, the thermocouple is the usual culprit. The thermocouple is a thin metal probe whose tip sits in the pilot flame; the flame heats it and it generates a tiny voltage that tells the gas valve "the pilot is burning, it is safe to keep gas flowing." When it fails or is misaligned, the valve assumes the pilot is out and shuts the gas off the instant you release the knob, which is the safety system working correctly.
Common fixes are repositioning the thermocouple so its tip is fully in the flame, cleaning soot off the probe and the pilot orifice, or replacing the thermocouple, an inexpensive part. If you have relit twice and it will not hold, or the pilot burns weak and yellow instead of a crisp blue, that is the point to call a pro. A thermocouple or pilot-assembly repair is modest, in the water heater repair cost range, and worth it over fighting a heater that keeps going dark.
Why pilots go out in the first place
A pilot that dies repeatedly is telling you something. Beyond a bad thermocouple, common causes are a draft or backdraft blowing it out (often a venting problem), a dirty pilot orifice starving the flame, a kinked or clogged pilot tube, or a failing gas control valve. A flammable-vapor sensor trip on newer FVIR-equipped heaters can also lock the unit out after it senses fumes, which requires a reset, not just a relight.
If relighting works but the pilot keeps going out over days, do not just keep relighting it, find the cause. Our guide to why a water heater pilot light will not stay lit walks through each suspect in order. Repeated outages around a gas appliance deserve a professional look, both for the heater’s sake and to rule out a venting or supply issue. If at any point the relight attempts coincide with a gas odor, stop and treat it as a leak.
Rather talk it through with a pro?
Calls are answered around the clock and routed to a licensed plumbing pro serving your area.