Symptoms
- Water is cold at every tap
- Pilot light appears out when you look in the viewing window
- Water heater is silent, no burner sound
- No error codes shown if it has a display
Likely causes
- CommonPilot light has gone outDrafts, a dip in gas supply, or a dirty thermocouple can extinguish the pilot.
- CommonFaulty thermocouple or thermopileThis safety sensor shuts off gas flow if it doesn't sense the pilot flame, and can fail with age.
- PossibleGas supply issue (valve closed or utility interruption)A closed shutoff valve or a supply issue affects the whole house's gas appliances.
- PossibleFailed control valve or igniterElectronic ignition units can fail at the igniter or control board.
What to do
- Check that the gas supply valve to the water heater is fully open (handle parallel to the pipe).
- Look at the control valve dial and make sure it's set to 'pilot' or 'on' as appropriate.
- Follow the manufacturer's printed relighting instructions on the tank exactly, since procedures vary by model.
- If the pilot lights but won't stay lit after releasing the button, the thermocouple likely needs replacing.
- If the pilot won't light at all, check for gas smell before doing anything further.
- If everything looks normal but there's no gas flow anywhere, check with your gas utility for an outage.
Tools and parts
- Flashlight
- Long lighter or matches (only if manual pilot lighting is specified)
Water heater thermocoupleSearch: “gas water heater thermocouple replacement”
When to call a pro
If the pilot won't stay lit after a fresh thermocouple, or you're not comfortable relighting it, call a licensed plumber or gas appliance technician.
Safety
Use caution
If you smell gas at any point, stop immediately, do not light anything, leave the area, and call your gas utility or 911 from outside.