Water heater pilot light won't stay lit

Symptoms

• Pilot lights fine but goes out within seconds of releasing the knob
• Have to relight it repeatedly
• No visible gas smell
• Igniter or spark works but flame doesn't hold

Likely causes

• CommonWorn or faulty thermocoupleThis small safety sensor senses the pilot flame; when it wears out, it shuts gas flow even with the pilot lit.
• CommonThermocouple not positioned correctly in the pilot flameIf it's bent away from the flame, it won't heat enough to keep the gas valve open.
• PossibleDirty or clogged pilot orifice causing a weak flameA small, weak flame may not heat the thermocouple sufficiently.
• PossibleDraft blowing the pilot out before it fully establishesAir currents near the water heater closet can disrupt the flame.

What to do

1. Follow your water heater's exact relighting instructions on the printed label.
2. Watch the pilot flame closely; it should be a steady blue flame that fully envelops the thermocouple tip.
3. If the flame looks small, weak, or yellow, the pilot orifice may need cleaning by a professional.
4. Hold the pilot button in for the full recommended time (often 30–60 seconds) before releasing to fully heat the thermocouple.
5. If it still goes out, check whether the thermocouple looks bent, corroded, or loose and reposition it gently if you're comfortable doing so.
6. If repositioning doesn't help, replacing the thermocouple, an inexpensive part, usually resolves it.

Tools and parts

• Adjustable wrench (for thermocouple replacement)
• Flashlight

When to call a pro

If replacing the thermocouple doesn't fix it, or you're not comfortable working on the gas control valve, call a licensed plumber or gas technician.

Safety