Furnaces & heating

Boiler pilot light is out

Relighting a boiler pilot follows the same safe process as a furnace: shut off, wait, then follow the printed instructions exactly.

Difficulty
Moderate
Time
10–15 minutes
DIY cost
$0
Pro cost
$100–$250

Symptoms

  • No flame visible at the pilot assembly
  • No heat or hot water depending on boiler type
  • Boiler unresponsive to the thermostat

Likely causes

  • CommonDraft or vibration extinguished the pilotA gust of air or a nearby door slam can blow out a small pilot flame.
  • CommonWeak thermocouple or flame sensorA worn sensor can let the pilot go out or fail to stay lit when relit.
  • PossibleGas supply interruptionA brief utility issue or closed valve stops gas to the pilot.
  • Less commonFailing gas valveAn internal valve fault can prevent gas from reaching the pilot reliably.

What to do

  1. Find the lighting instructions on the label near the boiler's gas control valve.
  2. Turn the control knob to Off and wait about 5 minutes for gas to clear.
  3. Turn the knob to Pilot, press and hold it, and light the pilot with a long lighter at the opening shown.
  4. Hold the knob in for the specified time until the pilot stays lit on its own.
  5. Release slowly, turn the knob to On, and confirm the boiler responds to a thermostat call for heat.
  6. If the pilot won't stay lit after two tries, stop and call a technician rather than continuing to relight it.

Tools and parts

  • Long lighter or fireplace match

When to call a pro

Call a technician if the pilot won't stay lit after two attempts, or anytime you smell gas near the boiler.

Safety

Use caution

Always follow the wait time before relighting and stop immediately if you smell gas.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.