When a water heater pilot won’t light, start with gas supply, ignition, and flame-sensing parts; clean the pilot and test the thermocouple.
Safety First Before You Try Anything
If you smell rotten-egg odor, hear hissing near gas lines, or see soot where it shouldn’t be, step outside with everyone in the home and call your gas utility or 911 from a safe spot. Don’t flip switches or relight anything. When the air is clear and you’re sure there’s no leak, you can move on.
Shut the water heater’s gas control to “OFF.” Let the burner area cool. Keep the area well-ventilated, and use a flashlight for visibility instead of open flame.
Pilot Light Not Igniting On A Gas Water Heater: Quick Checks
Most ignition issues trace back to a handful of parts and conditions. Your model may use a standing pilot with a thermocouple/thermopile, or an electronic system with spark or hot-surface ignition. The checks below cover both styles, with notes where steps differ.
Fast Diagnostic Map
Scan this list, pick the symptom that matches, then jump to the matching fix section below.
| Symptom | Likely Cause | Quick Check |
|---|---|---|
| No spark/click when pressing igniter | Dead piezo, loose wire, cracked button | Press while watching through window; inspect leads and connection tabs |
| Spark present, but no flame | Clogged pilot orifice, no gas flow | Listen for gas, clean pilot tube tip, confirm shutoff valves are open |
| Pilot lights but goes out when button released | Weak thermocouple/thermopile, misaligned sensor | Flame must wrap sensor tip; reseat or replace if weak |
| Pilot lights, then burner won’t fire | Control in lockout, bad flame signal, intake starved | Check status light code; clean air intake/filter |
| Pilot won’t light on windy days | Drafts, vent issues, missing door gaskets | Close drafts, reseat burner door, inspect vent rise and joints |
| Status light flashing error | Flame failure, limit trip, sensor fault | Decode label chart; follow the listed reset steps |
How The Pilot And Flame Sensor Work
Standing-pilot heaters keep a tiny flame burning. The flame heats a thermocouple or thermopile, creating millivolts that hold open the pilot safety valve. If the flame goes out, millivolts drop and gas shuts off. In electronic systems, a spark or hot surface lights gas and a flame sensor tells the control that fire is present; if no flame is sensed, gas stops and the control may lock out until you reset it.
Step-By-Step Fixes That Solve Most No-Light Situations
1) Confirm Gas Supply And Valve Positions
Trace the line from the meter to the heater. Inline shutoffs should be parallel to the pipe. The control knob on the heater should be set to “PILOT” when lighting. Light another gas appliance as a cross-check; if that one works, supply is likely fine at the house level.
If the supply was off or the tank is new, air in the line can slow ignition. Hold the pilot button per the lighting label to purge air, then try again. Don’t hold continuously for long stretches; use short, manufacturer-style attempts with cool-down between.
2) Restore The Spark Or Igniter Heat
Press the igniter while watching through the viewport. You should see a crisp spark at the pilot tip. No spark? Inspect the igniter lead for breaks, corrosion, or loose spade connections. Reseat the lead at both ends. If the piezo is cracked or mushy, swap it with a matching part. Hot-surface systems need a bright glow; a dull or broken element needs replacement.
3) Clean A Dirty Pilot Orifice
Dust, lint, and spider webs love pilot tubes. Shut gas “OFF.” Remove the pilot tube from the burner assembly if your model allows, or access the tip through the door. Use a soft brush and compressed air to clear debris. Do not ream the hole with a needle; you’ll change the flame shape. Reassemble, reset to “PILOT,” and try again.
4) Align And Test The Thermocouple Or Thermopile
The flame must wrap the sensor tip by 3/8–1/2 inch. Bend the bracket slightly so the tip sits in the blue cone. Loose threads at the gas control can drop millivolts; snug the connection by hand and add a small turn with a wrench—no overtightening. If the pilot still drops out when you release the button, replace the sensor. Many models use a combined pilot/thermopile assembly; match the part number for best results.
5) Clear The Air Intake And Flame Arrestor
Flammable-vapor-ignition-resistant (FVIR) heaters pull combustion air through a fine screen and a flame arrestor. Lint and dust can choke the intake and starve the pilot. With gas “OFF” and the burner cool, remove the lower door and any snap-in filter. Brush and vacuum the intake and arrestor plate. A flexible low-profile brush works well. Reinstall parts and try again.
6) Stop Drafts And Vent Problems
Open doors, leaky furnace rooms, and windy chimneys can blow out a small flame. Close nearby windows, seal the burner door, and check that the vent has a steady upward rise with tight joints. Backdraft marks (soot streaks) near the draft hood point to poor draft; correct vent run or call a technician to measure draft and check makeup air.
7) Decode Status Lights And Lockouts
Modern gas controls blink patterns that point to the fault. The chart sits on the control or the heater’s label. Common patterns include “low flame signal,” “flammable vapor sensor,” or “recycle.” Reset only as directed, then fix the root cause—usually a dirty sensor, weak thermopile, or starved intake.
How To Relight The Pilot The Right Way
Every tank has a lighting label. Follow that card for button order and hold times. The basic flow looks like this:
- Set the gas control to “OFF” and wait a few minutes.
- Turn to “PILOT.” Press and hold the pilot button to start gas to the pilot.
- While holding, press the igniter until the pilot flame appears.
- Keep holding for 30–60 seconds so the sensor heats up, then release. The flame should stay on.
- Turn the control to the desired temperature and watch the main burner light.
If your model uses electronic ignition without a standing flame, it may attempt lights on its own after you power it. If it gives up and shows an error code, use the code chart to guide the next step.
When A Sensor Or Control Is Failing
Thermocouples age out. Thermopiles can deliver low millivolts. A loose or sooty flame sensor on electronic systems sends a weak signal. If you’ve cleaned and aligned the parts and the pilot still drops when you release the button, swap the sensor. If the status light still calls out flame failure after a known good sensor and clean intake, the control may be the problem and a licensed tech should evaluate it.
Care That Keeps The Pilot Lighting Smoothly
Annual care pays off. Sweep and vacuum around the base, clean the intake screen, and brush the arrestor if your model has one. Keep a clear zone around the tank—no paint cans, no aerosols, no dusty boxes. Set a sensible temperature, and flush a bit of sediment from the tank a few times per year. Good air and a clean burner box make ignition consistent.
For general maintenance, see the U.S. Department of Energy’s guidance on storage water heaters. For flame-arrestor intake cleaning steps used on many FVIR tanks, review this manufacturer bulletin on flame arrestor cleaning and adapt to your exact model and label.
Detailed Fix Paths By Symptom
No Spark At The Pilot
Check the viewing port in darkness; a healthy spark is bright and sharp. If you get nothing, pull the igniter lead and check for corrosion. Reseat it until the spade feels snug. If the wire jacket is brittle or the ceramic is cracked, replace the assembly. Some models let you light with a long match during testing, but only if the label permits it and there’s no gas odor.
Spark Present, Still No Flame
You need gas at the pilot. Check that the shutoff is open. If the tank was moved or installed recently, purge air with short lighting attempts. Clean the pilot orifice with compressed air only. Confirm the pilot tube isn’t kinked. If there’s still no flame or sound of gas, the control may not be passing pilot gas; a pro can test outlet pressure ports.
Pilot Lights, Then Drops Out
That points to a weak flame signal. First, aim the flame at the sensor tip and secure all screws holding the bracket. Tighten the sensor nut at the control. If that doesn’t hold the flame, replace the sensor. On combo pilot/thermopile assemblies, match the OEM part so the bracket geometry lines up with the flame properly.
Burner Stays Off After Pilot Is Stable
Clean the intake and check the status light. Many controls won’t open the main valve if the flame signal is marginal or the intake is starved. Brush the arrestor and filter, clear lint, and try again. If the light still calls out “recycle” or “flame failure,” test with a new sensor before condemning the control.
Drafts Blow Out The Flame
Keep the burner compartment sealed and the door gasket intact. Close nearby doors and windows. Confirm the vent has enough vertical rise and no dips. If you share a chase with a furnace, the two appliances can fight for air; a tech can size makeup air and check draft with a gauge.
Relighting Tips For Electronic Ignition Models
These units won’t have a standing flame. You’ll hear clicks or see a glow bar, then the control checks for flame. Many controls try a set number of times, then lock out. Unplug or follow the reset sequence on the label, clean the sensor, and retry. If it still fails, don’t keep cycling power endlessly; track down intake, gas flow, or sensor issues first.
When To Stop DIY And Call A Licensed Technician
| Situation | Why You Should Pause | Next Step |
|---|---|---|
| Any gas odor, hissing, scorched wiring | Leak or unsafe combustion risk | Leave the area; call utility or 911 |
| Repeated lockouts with clean intake and new sensor | Control, valve, or vent sizing issue | Schedule service to test pressures and draft |
| Pilot tube damage or stripped control threads | Improper sealing can leak gas | Have a pro replace parts and leak-check |
| Soot streaks, rolling flame | Poor draft or blocked exchanger | Vent inspection and combustion test |
| Flammable vapor sensor trips | Possible spill near heater | Address the spill; reset per label or call service |
Simple Maintenance Schedule
Every month: keep the base area clear and vacuum dust. Every few months: brush the intake screen and, if applicable, the arrestor. Twice per year: test the temperature and pressure relief valve per your label. Every few years: drain a few liters from the tank to pull sediment. If you live in a dusty space or run clothes dryers nearby, shorten the cleaning interval.
Pro-Level Checks You Can Request
If a tech visits, ask for a draft test at the draft hood, pilot and manifold pressure checks, and a sensor millivolt or microamp reading. These quick numbers confirm whether the vent, gas control, and flame signal are in range. Keep the service tag for the next time.
Relight Card Lives On The Heater For A Reason
Your label is the final word for hold time, reset steps, and any model-specific warnings. If you replaced a burner door or igniter, move the card to the new panel so it stays visible. Snap a photo of it now, while the light is working, and store it in your phone.
Quick Checklist Before You Call It Fixed
- The pilot ignites on the first or second try.
- The flame wraps the sensor tip with a steady blue cone.
- The status light shows normal operation.
- The main burner lights cleanly with no rumble or rolling flame.
- The intake screen and burner box are clean and reassembled.
- There’s clear space around the heater with no chemicals nearby.
If the light stays steady through a few cycles and the burner fires cleanly, you’ve solved it. If not, the next best step is a pressure and draft check by a licensed pro.