If your pilot light keeps going out, the most likely culprits are a faulty thermocouple, a blocked pilot orifice, or a draft problem. These are not random inconveniences. A pilot that repeatedly extinguishes is usually the appliance’s safety system doing its job to prevent unburned gas from building up inside your home. Treat repeated outages as a fault to diagnose, not a habit to manage.
Before anything else:
- If you smell gas at any point, stop immediately. Leave the property, leave the door open as you go, and call emergency services (000) or your gas supplier from outside. Do not attempt to relight the appliance.
- If there is no gas smell, check whether the flame dies within 10–30 seconds of release (thermocouple fault), flickers yellow or orange (blocked orifice or poor combustion), or blows out during wind or when the main burner fires (draft or airflow issue).
- If the pilot goes out more than twice after relighting, or if you are unsure about any of the symptoms above, stop and call a licensed gas fitter.
Table of Contents
- What a pilot light does and why the safety loop matters
- Why does a pilot light keep going out? The most common causes
- How to safely relight a standing pilot
- Simple checks you can do yourself — and what to leave to a professional
- When to call a licensed plumber or gas fitter
- What does a pilot light repair cost in Australia?
- How Priority Plus Plumbing diagnoses and fixes repeated pilot outages
- Your 24–48 hour checklist after a pilot outage
- Key takeaways
- The fault your appliance is trying to tell you
- Priority Plus Plumbing is ready when your pilot won’t stay lit
- FAQ
What a pilot light does and why the safety loop matters
A standing pilot is a small, continuously burning flame that ignites the main burner when your appliance calls for heat or hot water. Older gas water heaters, space heaters, and some ducted heating systems use them. Newer appliances use electronic ignition instead, which lights the burner on demand and carries no standing flame.
The safety loop works like this: the pilot flame heats a component called a thermocouple (or, in newer systems, a flame sensor). That heat generates a small electrical signal, measured in millivolts, which holds the gas valve open. If the flame goes out, the signal drops, the valve closes, and gas stops flowing. The pilot safety valve is what prevents raw gas from entering an unlit appliance. When the thermocouple is weak or the flame is too small to heat it properly, the valve closes even when the pilot appears to be burning, and the appliance shuts off.
Understanding this loop tells you something useful: most pilot ignition problems trace back to either the flame itself (too small, wrong colour, wrong position) or the sensor reading it (dirty, misaligned, or failing).
Why does a pilot light keep going out? The most common causes
1. Dirty or blocked pilot orifice
A clogged orifice restricts gas flow to the pilot, producing a weak, yellow, or flickering flame. That small flame cannot generate enough heat to sustain combustion when conditions change, such as when a draft passes through or the main burner fires. The symptom is a flame that looks thin, pale, or wavering rather than a crisp blue cone.
2. Faulty or dirty thermocouple
This is the single most common cause of a pilot that dies 20–30 seconds after you release the control knob. The thermocouple tip needs to sit directly in the pilot flame to generate a sufficient millivolt signal. Dust, corrosion, or physical misalignment reduces that signal below the threshold the gas valve needs to stay open. Correct positioning means the flame engulfs the tip; even a small shift causes intermittent shut-offs.
Pro Tip: After relighting, hold the control button for the full 20–30 seconds. If the pilot holds while you press but dies the moment you release, the thermocouple is almost certainly the fault.
3. Drafts and airflow problems
Gaps around doors, poorly sealed utility cupboards, and open windows near the appliance can all blow out a pilot flame. A more subtle version of this problem occurs when the main burner fires and the sudden rush of combustion air extinguishes the pilot. This points to a weak pilot flame or a clogged orifice rather than an external draft.
4. Low or fluctuating gas pressure
If gas pressure at the appliance drops below the manufacturer’s specification, the pilot flame shrinks and becomes unstable. This can happen during periods of high demand on the gas network, or if there is a partial obstruction in the supply line. You may notice the pilot holds on calm days but fails when other gas appliances are running simultaneously.
5. Failing gas control valve
The gas control valve regulates flow to both the pilot and the main burner. When the valve’s internal coils begin to fail, they may not hold the pilot circuit open reliably. Deeper faults such as failing gas valve coils are beyond DIY repair and require a licensed technician to diagnose and replace.
6. Venting or flue obstructions
A blocked or partially obstructed flue can cause exhaust gases to back-draft into the combustion chamber, smothering the pilot. Bird nests, debris, and collapsed flue liners are common culprits in Australian homes, particularly after summer storms or extended periods without use.
7. Moisture, corrosion, or debris ingress
Humidity and corrosion can destabilise pilot flames and degrade thermocouple performance over time. In coastal areas of Sydney and the Sutherland Shire, salt-laden air accelerates corrosion on pilot assemblies and gas valve components. Moisture ingress from a leaking flue or condensation inside the appliance cabinet can also cause intermittent outages that are difficult to reproduce on demand.
How to safely relight a standing pilot
Only attempt relighting if there is no smell of gas and the area is well ventilated. Check the appliance label first; manufacturer instructions always take precedence over general guidance.
- Turn the gas control knob to “Off” and wait at least five minutes for any residual gas to clear before proceeding.
- Locate the pilot assembly. Remove the access panel if needed. Have a long-reach lighter or a fireplace match ready.
- Turn the control knob to “Pilot.” Press and hold the knob down (or the separate red ignition button, depending on your appliance model).
- Bring the flame to the pilot orifice and ignite. Continue holding the control knob down.
- Hold for 20–30 seconds. Manufacturers require this warm-up time so the thermocouple heats sufficiently to generate the millivolt signal that keeps the gas valve open. Releasing too early is the most common reason a freshly lit pilot goes straight back out.
- Slowly release the knob. Watch the flame. A healthy pilot burns blue, sits steady, and stays lit. A flame that dies on release points to a thermocouple fault.
- Turn the control to your desired setting once the pilot holds. Replace the access panel.
If the pilot fails to hold after two attempts, do not keep trying. Call a licensed gas fitter to inspect the appliance.
Simple checks you can do yourself — and what to leave to a professional
There are a handful of low-risk checks worth doing before you call a plumber.
Safe DIY checks:
- Observe flame colour. A healthy pilot burns blue. Yellow or orange indicates incomplete combustion, often from a dirty orifice or poor air supply.
- Check for drafts near the appliance. Close nearby windows and doors, then attempt a relight to see if the pilot holds more reliably.
- Gently remove loose dust or debris from around the pilot area using a soft brush or a brief burst of compressed air. Do not probe inside the orifice.
- Clear any obvious debris from external vent openings (leaves, insect nests) that may be restricting airflow.
- Perform the warm-up release test described above to isolate a thermocouple fault.
What you must not attempt:
- Never bypass or disconnect the thermocouple or any other safety device.
- Do not attempt to clean the pilot orifice with metal tools or probes; you risk enlarging or damaging it.
- Do not attempt gas valve repairs or replacement. Under Australian law, any work on gas valves, gas lines, or internal gas fittings must be carried out by a licensed gas fitter. Attempting this work unlicensed is illegal and dangerous.
- Do not relight the appliance repeatedly if you can smell gas or if the pilot fails more than twice in a row.
A licensed gas fitter can also use a multimeter to test thermocouple resistance; healthy probes typically read in the range of 1–10 Ohms, and readings outside this range confirm replacement is needed. This is a diagnostic step for the technician, not a homeowner task.
When to call a licensed plumber or gas fitter
Some situations require professional attendance, and knowing the urgency level helps you act correctly.
Call emergency services (000) or your gas supplier immediately if:
- You smell gas anywhere in or around the property.
- A carbon monoxide detector activates.
- The flame burns yellow or orange and you cannot ventilate the space quickly.
Call a licensed gas fitter urgently (same day) if:
- The pilot extinguishes immediately every time you release the control, even after holding for the full 20–30 seconds.
- You notice soot around the appliance or an exhaust smell near the flue outlet.
- The pilot has gone out more than twice in a short period with no obvious external cause.
Book a routine inspection if:
- The pilot goes out occasionally and responds to a single relight, but the frequency is increasing.
- You have cleaned around the pilot area and the problem persists.
During a professional visit, the technician will check the pilot orifice condition, test the thermocouple or flame sensor output, measure gas pressure at the appliance, test the gas valve coil function, inspect the venting and flue for obstructions, and perform combustion and carbon monoxide testing. Before the technician arrives, turn the appliance off at the gas control knob, ventilate the room, and note when the outages started and how often they occur.
What does a pilot light repair cost in Australia?
Costs vary by location, appliance type, and the extent of the fault. The figures below reflect typical ranges for Sydney and the Sutherland Shire.
| Repair type | Typical cost (AUD) | Typical time |
|---|---|---|
| Call-out and diagnosis | — | Same day |
| Pilot orifice cleaning | — | 30 minutes |
| Thermocouple replacement | — | 1–2 hours |
| Gas valve replacement | — | 2–4 hours |
| Full appliance replacement | — | 1–2 days |
Thermocouple parts are relatively inexpensive, but labour and testing add to the total. If your appliance is more than 10–12 years old and has needed multiple repairs, replacement is often more cost-effective than continuing to service an ageing unit. A licensed plumber can give you a repair versus replacement assessment based on the appliance’s condition and parts availability.
How Priority Plus Plumbing diagnoses and fixes repeated pilot outages
Priority Plus Plumbing attends gas appliance faults across Sutherland Shire and Sydney, 24 hours a day, seven days a week. Every job is handled by a licensed gas fitter, not a general handyman, which matters when the fault involves gas valve testing or combustion checks.
What the service includes:
- 24/7 emergency attendance for urgent gas and hot water faults.
- On-site thermocouple and flame sensor testing, pilot orifice inspection, and gas pressure measurement.
- Combustion testing and carbon monoxide checks as standard on gas appliance jobs.
- Transparent, upfront quotes before any work begins, with no hidden call-out surprises.
- Workmanship guarantee on all repairs and replacements.
Sydney’s coastal climate, particularly in the Sutherland Shire, means salt air corrosion on pilot assemblies and gas valve components is a more frequent cause of failure than in inland areas. The team is familiar with this pattern and checks for corrosion-related thermocouple drift as a routine step, rather than replacing parts unnecessarily. Older brick veneer and fibro homes in the area also tend to have less-sealed utility spaces, making draft-related pilot failures more common than in newer builds.
During a visit, the technician will isolate the gas supply, run through a full diagnostic sequence, provide a written cost estimate, complete the repair, and retest the appliance before leaving.
Your 24–48 hour checklist after a pilot outage
Right now:
- [ ] Check for gas smell. If present, leave immediately and call 000.
- [ ] If no smell, ventilate the space and turn the appliance off at the gas control.
- [ ] Note the symptoms: does the pilot die on release, blow out in wind, or fail when the main burner fires?
Within the next few hours (if safe to attempt a relight):
- [ ] Follow the step-by-step relighting procedure above.
- [ ] Hold the control for the full 20–30 seconds.
- [ ] If the pilot fails twice, stop and book a licensed gas fitter.
Within 24–48 hours:
- [ ] Take photos of the pilot assembly and flame colour if you can do so safely.
- [ ] Note how many times the outage has occurred and over what period.
- [ ] Book a licensed plumber if the problem is recurring, even if the last relight held.
- [ ] Ask the technician for a written quote before authorising any gas valve or parts work.
Key takeaways
A pilot light that keeps going out almost always points to a thermocouple fault, a blocked orifice, or a draft problem — and repeated failures need a licensed gas fitter, not repeated relighting.
| Point | Details |
|---|---|
| Safety comes first | If you smell gas, leave the property immediately and call 000 before anything else. |
| Thermocouple is the most common fault | A pilot that dies within 30 seconds of releasing the control almost always means the thermocouple needs cleaning or replacement. |
| Hold for 20–30 seconds when relighting | This warm-up time lets the thermocouple generate the signal that keeps the gas valve open. |
| Gas valve and line work is licensed work | Under Australian law, any repair beyond basic cleaning must be done by a licensed gas fitter. |
| Priority Plus Plumbing | Provides 24/7 licensed gas fitter attendance across Sutherland Shire and Sydney, with upfront pricing and a workmanship guarantee. |
The fault your appliance is trying to tell you
Most homeowners treat a pilot that keeps going out as a nuisance to manage rather than a message to read. That framing gets people into trouble. The safety circuitry in a gas appliance is not malfunctioning when it shuts off the pilot; it is doing exactly what it was designed to do. The inconvenience is the point.
What concerns me most is the habit of repeated relighting without investigating the cause. Every time you relight without understanding why the pilot failed, you are accepting a small but real risk. A thermocouple that is drifting toward failure will eventually stop generating any signal at all. A gas valve with a failing coil may not close reliably. Neither of these faults announces itself loudly.
The other thing homeowners consistently underestimate is the role of the local environment. Coastal Sydney properties, particularly in the Sutherland Shire, deal with salt air corrosion at a rate that inland homeowners simply do not. A thermocouple that might last 10 years in a dry inland climate can degrade noticeably faster near the coast. That is not a reason to panic; it is a reason to have the appliance inspected on a reasonable schedule rather than waiting for a failure.
The practical rule is straightforward: one outage, try a relight. Two outages in a short period, call a licensed gas fitter. Any smell of gas, leave first and call from outside.
Priority Plus Plumbing is ready when your pilot won’t stay lit
When a pilot light fault is beyond a simple relight, you need a licensed gas fitter on-site, not a callback queue. Priority Plus Plumbing responds 24/7 across Sutherland Shire and Sydney, with licensed gas fitters who carry out full combustion testing, thermocouple replacement, and gas valve diagnostics in a single visit.
Every job comes with a transparent, upfront quote before work begins and a workmanship guarantee when it is done. No surprises on the invoice, no guessing about whether the repair was done correctly.
When you call, have the following ready: the appliance make and model (usually on the front panel or inside the access cover), a brief description of when the outages started and how often they occur, and whether you have noticed any unusual flame colour or smell.
For urgent gas appliance faults, book an emergency attendance or call Priority Plus Plumbing directly. For hot water system repairs and replacements across Sydney, visit the hot water repairs page to see what a service visit covers.
Useful sources and further reading
The following sources informed this article and are worth bookmarking for further reference.
- A.O. Smith: How to relight a water heater pilot light — manufacturer guidance on pilot relighting and safety valve behaviour.
- Wikipedia: Pilot light — background on standing pilots versus electronic ignition systems.
- DIY Stack Exchange: Why does my pilot light keep going out? — practitioner discussion on thermocouple positioning and fault diagnosis.
- Simco Direct: Heating system controls explained — useful background on how built-in safety mechanisms work in heating systems.
Always follow the instructions on your appliance’s label and the manufacturer’s manual. For any gas valve, gas line, or internal fitting work, use a licensed gas fitter. In Australia, unlicensed gas work is illegal and voids appliance warranties.
This article provides general information only and is not a substitute for professional advice. Confirm current licensing requirements and safety rules with your state or territory gas regulator or a qualified gas fitter.
FAQ
How do you fix a pilot light that keeps going out?
Start by relighting with the full 20–30 second thermocouple warm-up. If the pilot dies on release, the thermocouple likely needs cleaning or replacement by a licensed gas fitter.
What causes a pilot light to keep going out on a water heater?
The most common causes are a faulty or dirty thermocouple, a blocked pilot orifice, or a draft near the appliance. A failing gas control valve is less common but also possible.
How do you clean a thermocouple on a gas heater?
Turn off the gas and allow the appliance to cool completely. A licensed gas fitter can remove the thermocouple, clean the tip with fine steel wool, check its resistance, and reposition it so the pilot flame fully engulfs the tip.
Why does my pilot light go out every few months?
Intermittent outages that worsen over time usually indicate a thermocouple nearing the end of its service life, or gradual corrosion on the pilot assembly. In coastal areas like the Sutherland Shire, salt air accelerates this process. A routine inspection will confirm whether cleaning or replacement is needed.