Last Updated on June 7, 2026 by Anta Plumbing Master Plumber
A water heater pilot light won’t usually stay lit because of a worn thermocouple, a clogged pilot orifice, a draft, or a failing gas valve that cuts the flame on release.
That single dead flame means no hot water, and it always seems to strike on the coldest morning of the year. Older basements and long winters make the problem worse, so the cause is rarely random. Pinning it down takes a clear, ordered check. Read on to find the real cause, the safe fixes, the warning signs, and what a repair should cost.
Why Your Water Heater Pilot Light Won’t Stay Lit
A dead pilot almost always comes down to one thing. The flame, the sensor reading it, or the gas feeding it. Here are the causes we find most in GTA homes.
Dirty or Faulty Thermocouple
This tops the list every single time. The thermocouple is a safety sensor in the pilot flame. Heat tells it to keep the gas valve open.
Over time, soot coats it, or the metal wears out. Then it cannot read the flame, so it cuts the gas. The classic sign? Your pilot dies the second you release the knob.
Dirty Pilot Tube or Pilot Orifice
The pilot tube carries gas to the flame. Carbon and grime slowly block it. Toronto’s hard Lake Ontario water speeds this up, since scale and sediment collect around the burner. A choked tube leaves a thin, struggling flame.
Faulty Thermopile (For Newer Water Heaters)
Newer gas units often use a thermopile instead. It bundles several thermocouples in series. That extra voltage runs the electronic controls.
Have an electronic gas control valve? Then you likely have a thermopile. A reading under 450 millivolts usually signals failure. Loose, corroded connectors trigger it often. Our licensed technicians test these readings on-site.
Damaged Gas Control Valve
The gas control valve feeds both the pilot and the burner. As it ages, it can starve the pilot without warning. That makes it a safety risk, not a DIY task. Shut off the gas and book a licensed plumber.
Insufficient Gas Supply
A weak gas feed cannot hold the flame. First, confirm the gas shut-off valve is fully open. Deep freezes matter too, since peak demand on the Enbridge Gas grid can drop your pressure. If your stove and furnace also sputter, the fault is your supply or your gas line.
Drafts Blowing Out the Pilot Flame
Drafts trouble older GTA basements and garages the most. Century homes in Leaside, The Beaches, and Cabbagetown tuck tanks into cold corners. A window gust or chimney downdraft can kill the flame. If your pilot only dies on windy days, suspect drafts first.
Faulty Safety Sensors
Some heaters add a cut-off sensor inside the valve. Its job is guarding against overheating. On a few models, it fails too soon. Then it trips your pilot for no real reason.
Venting Problems
Your flue vents exhaust gases safely outdoors. A blocked or loose flue is a real danger. It can stall the heater or push carbon monoxide inside. Rust, soot, or moisture on the vent means you need a professional inspection right away.
Condensation Extinguishing the Pilot
By January, Lake Ontario water runs ice cold. That chilly inflow forms condensation inside the tank. Drops then fall onto the pilot and douse it. High-efficiency units run cooler exhaust, which adds to the problem.
How to Fix a Water Heater Pilot Light That Won’t Stay Lit
A few fixes suit a confident homeowner. The rest belong to a licensed gas technician. Get a step wrong here, and you risk a gas leak. If you feel unsure at any point, our Toronto water heater repair team handles the whole job safely.
Clean the Pilot Assembly
Shut off the gas before you touch anything. Clear the orifice and tube with a thin wire or compressed air. Clean gas flow often revives a sputtering pilot.
One caution: never bend or force the thin pilot tube. A kinked tube can leak gas. Spot any damage, and call a licensed plumber instead.
Reposition the Thermocouple
The tip belongs right inside the pilot flame. If it has slipped, ease it gently back. Proper contact lets it read the flame again. A small nudge often does the trick.
Tighten Loose Connections
Loose connectors drag down voltage readings, mostly on thermopiles. Make every connection clean and tight. Corrosion here muffles the signal to the gas valve. Hand-tightens only, since over-torquing strips the threads.
Replace the Thermocouple
Cleaning will not save a truly worn part. The piece itself costs under fifteen dollars. But it sits at the gas valve, where the work turns serious. You must shut the gas, swap it, then leak test every joint. We send a licensed plumber so the repair stays safe and code compliant.
Replace a Faulty Thermopile
A low thermopile reading calls for a new one. The burner work is fiddly and precise. A poor fit can void your warranty, too. Our Oakville water heater technicians fit it and verify the millivolt output.
Replace the Gas Control Valve
This part costs more and demands real gas expertise. Swapped the thermocouple, but the pilot still quits? Then the valve electromagnet is the suspect. Never open a sealed burner chamber yourself. On a tank past ten years, a new water heater usually beats a new valve.
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How to Relight a Water Heater Pilot Light
Safety Precautions Before Relighting
Do you smell gas? Then do not relight. Step outside and call Enbridge Gas at 1-866-763-5427 or 911 from a neighbour’s home. Brands like Rheem, Bradford White, and A.O. Smith vary slightly. Read the label on your tank first.
Step-by-Step Pilot Light Relighting Instructions
- Turn the gas control to Off. This halts the gas flow fully.
- Wait for residual gas to clear. Give it five minutes, with no shortcuts.
- Set valve to Pilot. Drop the temperature dial to its lowest mark first.
- Ignite the pilot. Hold the knob down, then click the igniter or use a long lighter.
- Hold the reset button. Keep it down 60 seconds so the thermocouple warms up.
- Confirm flame stability. Let go slowly; a steady blue flame is the goal.
- Return control to On. Set your temperature back to 49 °C (120°F).
Did it die again despite a careful try? Then stop. Repeat failures need a professional diagnosis, not another match.
When a Pilot Light Problem Becomes Dangerous
Most pilot trouble is a hassle, not a hazard. Still, a few signs demand quick action.
- A gas smell near the tank is serious. Leave the home and call Enbridge Gas or 911 from outside. Light nothing until a pro clears it.
- A pilot who keeps quitting masks a deeper fault. Relighting it on repeat only hides the cause. Have it properly diagnosed instead.
- Dark soot or staining points to bad combustion. That usually means a venting or backdraft fault. It can leak carbon monoxide indoors.
Signs of Carbon Monoxide Issues
Carbon monoxide has no colour and no smell. Headaches, dizziness, or nausea near the tank are warnings. As of January 1, 2026, Ontario’s Fire Code requires a CO alarm on every storey with a gas appliance. If yours sounds, get out and call 911.
- Check for melted plastic rings near the pipes. Look for moisture beads on the tank top. Both hint that the unit has backdrafted before.
- Rust on the valve or fittings is a warning sign. Corrosion turns into leaks over time. Get a technician to inspect it early.
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When to Call a Professional Plumber
In Ontario, gas work falls under the TSSA (Technical Standards & Safety Authority). A licensed G2 technician handles home gas appliances. You can verify any licence number for free at tssa.org.
- You relit it carefully, more than once, with no luck. That points to a worn part, not bad timing. A technician finds the real cause.
- Fresh thermocouple in, yet the pilot keeps dying? Suspect the gas valve next. This fix needs proper tools and training.
- A blocked or detached flue is dangerous. It risks pushing carbon monoxide into your home. Hand this inspection to a pro.
- Any whiff of gas means stop now. Leave the house and call Enbridge Gas or 911. Do not relight until it is cleared.
- A sounding CO alarm is an emergency. Get everyone outdoors and dial 911. Return only when responders clear it.
- Does the unit keep shutting itself off? A sensor or valve is likely failing. No hot water tonight in Scarborough or Markham? We reach you fast across the GTA.
What Is the Water Heater Pilot Light Repair Cost?
Costs in the GTA vary with the part, the access, and the time of the call. The table below sets realistic expectations for each repair.
| Repair | Typical GTA Cost (CAD) |
| Thermocouple replacement | $100 to $200 |
| Thermopile replacement | $150 to $250 |
| Gas control valve replacement | $150 to $550 |
| Pilot assembly cleaning | Included in the diagnostic |
| Diagnostic/call-out fee | $50 to $150 |
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How to Prevent Future Pilot Light Problems
A bit of upkeep spares you cold mornings. These habits keep your pilot burning steadily.
Schedule Annual Water Heater Maintenance
Set a yearly check with a licensed plumber. During a service visit, we inspect the pilot, thermocouple, gas line, and venting. Ontario advises annual checks on every fuel-burning appliance.
Keep the Area Around the Heater Clean
Clear away clutter, lint, and dust. This protects the combustion air supply. A tidy space helps the flame burn clean.
Inspect Venting Regularly
Scan the flue for rust or blockages. Watch for soot near the draft hood. Spotting issues early stops dangerous backdrafts.
Address Draft Issues
Seal gaps and weatherstrip your windows and doors. This pays off through harsh GTA winters. Fewer drafts mean a steadier pilot flame.
Soften Your Hard Water
GTA water runs hard, from Toronto’s 7 to 8 grains up to Brampton’s 12 to 15. That scale stacks up and overworks the burner. A water softener trims sediment and lengthens your tank’s life.
Replace Worn Components Early
Thermocouples and valves fade with age. Swap them before they quit entirely. Acting early beats an emergency breakdown.
Test Safety Devices Periodically
Test your carbon monoxide alarms every month. Refresh batteries and old units on time. This keeps you safe and within the new Ontario rule.
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Frequently Asked Questions
Why does my pilot light stay lit only when I hold the button down?
Your thermocouple is the prime suspect. It cannot read the flame, so it cuts the gas. Cleaning may help; often a swap is needed.
Can a bad thermocouple cause a pilot light to go out?
Yes, and it is the most common reason. A worn or dirty thermocouple closes the gas valve. The pilot then cannot hold.
Is it safe to relight a pilot light yourself?
Usually, yes, if you follow the label steps. But stop the moment you smell gas. Call a pro if it keeps quitting.
Why does my pilot light keep going out after a few minutes?
A failing thermocouple often works only briefly. It lights fine, then drops soon after. That pattern points right at the sensor.
How much does it cost to fix a pilot light problem?
A thermocouple repair runs about $150 in Toronto. A gas valve can reach $500. For a firm number, we quote on site.
Can a gas control valve cause pilot light failure?
Yes, a worn valve can starve the pilot. Diagnosing it takes a licensed technician. Never try this repair on your own.
Should I replace my water heater if the pilot won’t stay lit?
Not always; a thermocouple fix often does it. But GTA tanks usually last 8 to 14 years. Past ten, weigh replacement seriously.
Final Thoughts
A dead pilot light rarely spells the end of your tank. Begin with the easy checks: the thermocouple and any nearby drafts. If it still will not hold, that is your signal to call a licensed pro.
Anta Plumbing & Drain is licensed, insured, and available 24/7 across Toronto, Oakville, Mississauga, Brampton, and the wider GTA. We come to you, diagnose the fault, and quote it straight before we begin. Book your water heater repair, or call us the moment your hot water quits.
