Water Heater Pilot Light Won't Light: Causes and Safe Fixes
Why a gas water heater pilot light will not light or stay lit, the safe checks to try, and when to stop and call a pro.
A pilot light that will not light or keeps going out leaves you without hot water. Some causes are easy to check, but gas appliances come with safety rules you should not skip.
The Short Answer
The most common causes are a worn thermocouple, a dirty pilot tube, a gas supply problem or a draft that blows the flame out. If you ever smell gas, leave the home and call your gas utility or 911 before doing anything else.
Safety First
If you smell rotten egg odor, do not light anything, do not use switches, and leave. Call your gas provider from outside. Only attempt relighting if there is no gas smell and the manufacturer's instructions on the heater are clear to you.
Common Causes
Thermocouple or thermopile failure
This sensor tells the gas valve the pilot is lit. When it wears out, the pilot will not stay on.
Dirty pilot tube or orifice
Dust and debris can weaken the flame.
Gas control valve
A failing valve may not let gas flow to the pilot.
Drafts or venting trouble
Back drafts or a blocked vent can blow out the flame and are a safety concern.
What You Can Safely Check
- Is the gas supply valve open?
- Is the control set to pilot, not off?
- Did the heater run out of gas, or is another gas appliance working?
If it still will not light, the next steps involve parts and gas connections that are best left to a technician. See our gas water heater repair service.
When to Replace
An older unit with repeated pilot problems may be at the end of its life. Compare options in repair or replace, or start with our no hot water guide.
Frequently asked questions
Why does my pilot light keep going out?
A worn thermocouple, a dirty pilot, drafts or a gas supply issue are common reasons.
Is it safe to relight a water heater pilot light myself?
Only if there is no gas smell and you follow the manufacturer's instructions. If you are unsure, call a professional.
What does it cost to replace a thermocouple?
It is usually a modest repair, though the total depends on the unit and labor, so ask for a written estimate.
What should I do if I smell gas near my water heater?
Leave the home, avoid switches and flames, and call your gas utility or 911 from outside.
Water heater acting up?
Statewide service across Arizona. Call 1 (844) 495-3109 now.