Water Heater Pilot Light: How to Light It and Fix Problems

Last updated: July 2026 · Reviewed against A.O. Smith and Rheem operating instructions

If your gas water heater has no hot water, the pilot light is the first thing to check — if it has gone out, the burner cannot fire. Relighting it is usually a simple DIY job, but if the pilot will not stay lit, the cause is almost always a dirty or failed thermocouple. Here is how to find, light, and troubleshoot your water heater’s pilot light safely.

⚠️ Before relighting, if you smell a strong gas odor, stop. Leave the house and call your gas utility. Only relight if there is no significant gas smell.

Where Is the Pilot Light?

The pilot is at the bottom of the tank, behind a small access cover or panel near the gas control valve. On older units you can see the flame through a small window; on newer sealed-combustion units, the pilot is behind a cover and lit with a built-in igniter button. Check your unit’s type before starting — the lighting steps differ slightly.

How to Light the Pilot Light

1. Turn the gas control dial to OFF and wait 5 minutes for any gas to clear.
2. Turn the dial to PILOT.
3. Press and hold the dial (or the pilot button) down — this releases gas to the pilot.
4. While holding, press the red igniter button repeatedly until the pilot lights (or hold a long lighter to the pilot on manual units).
5. Keep holding the dial down for 30–60 seconds after the flame lights, then release.
6. Turn the dial to ON. The burner should fire when there is a call for hot water.

Pilot Won’t Stay Lit? It Is the Thermocouple

The single most common pilot problem: the flame lights while you hold the dial, but goes out the moment you release it. This is the thermocouple — a safety sensor that must sense the pilot flame to keep the gas valve open. When it is dirty, bent out of the flame, or worn out, it fails to signal and shuts the gas off. Cleaning it or replacing it (a $10–$20 part) usually fixes it. Full guide: replacing the thermocouple on a water heater.

Other Reasons the Pilot Goes Out

• Dirty pilot orifice: a clogged tip produces a weak flame that cannot heat the thermocouple.
• Drafts: a strong draft near the unit can blow the pilot out.
• Flex tube or gas supply issue: low gas pressure or a kinked pilot tube starves the flame.
• Failed gas control valve: less common, but a faulty valve will not hold the pilot; this needs a pro.

When to Call a Pro

Call a professional if you smell gas, if a new thermocouple still will not hold the pilot (pointing to the gas valve), or if you are not comfortable working around the gas control. If the pilot lights fine but you still have no hot water, the problem is elsewhere in the system.

FAQ

Why does my water heater pilot light keep going out?

The most common cause is a dirty or failing thermocouple that no longer senses the flame and shuts off the gas. Other causes include a clogged pilot orifice, a draft, or low gas pressure. Start by cleaning or replacing the thermocouple.

How do I know if my pilot light is out?

You will have no hot water, and on units with a window you will see no small flame at the burner. Many units also have a status light that blinks a code indicating the pilot is out.

Is it safe to relight a water heater pilot myself?

Yes, if there is no strong gas smell. Follow the instructions on the unit’s label, turn the gas off and wait 5 minutes before relighting, and never force anything. If you smell significant gas, leave and call your utility instead.