Every gas or propane water heater relies on the same chain: fuel arrives, something lights it, the heater confirms a flame is present, and only then does the gas control keep the burner supplied. If any link fails, the control shuts off the gas as a safety measure. That's why "the pilot keeps going out" is almost always a symptom rather than the problem.
No hot water on a gas unit? Start here
- Are other gas appliances in the home working normally?
- Is there a code on the display, or a status light blinking on the gas control?
- Have you heard clicking, a whoomp on lighting, or seen soot near the top or base?
Share the answers when you call, and leave the unit's controls alone.
The three kinds of ignition
Standing pilot. Common on standard gas tanks. A small flame burns continuously and lights the main burner when the tank calls for heat. A thermocouple or thermopile sitting in the pilot flame generates a tiny signal that tells the gas control the flame is there.
Electronic or intermittent ignition. Found on many newer and power-vented tanks. There's no permanent pilot; an igniter lights the burner on demand and a flame sensor confirms it.
Tankless ignition. Tankless units use electronic ignition every time water flows, with a flame rod or similar sensor and a circuit board managing the sequence. Faults usually show as codes.
Symptoms and what they usually mean
- Pilot won't stay lit. Most often the thermocouple or flame sensor, sometimes a dirty pilot, a draft, or a clogged air intake.
- Pilot lit but burner won't fire. Often the gas control or thermostat side of the control, or a burner problem.
- Clicking without lighting. On electronic and tankless ignition, a worn igniter, a flame-sensing fault or a supply issue.
- A whoomp on lighting. Delayed ignition. Gas accumulates before it lights. Have it checked promptly.
- Yellow, lazy or sooty flame. Incomplete combustion from restricted air, a dirty burner or venting trouble.
- Burner lights, then cuts out. Can point to venting, a draft safety device doing its job, or a sensing problem.
California patterns
Garage dust and lint. Most gas water heaters in the southern metros and the Central Valley live in garages alongside dryers, workbenches and storage. Many modern tanks draw combustion air through a flame arrestor at the base, and lint or dust can clog it until the burner can't breathe. Keeping the area around the heater clear is the single most useful habit.
Exterior closets. Wind can gust through louvered doors, and sun-heated closets are hard on components. Both show up as intermittent pilot outages.
Propane in the foothills and mountains. Propane appliances must be set up for propane, and a low or empty supply tank causes outages that look like a heater fault. Higher-elevation communities may also need combustion appliances configured appropriately; that's a question for the technician and the manufacturer's guidance, not something to adjust yourself.
Seismic strapping. A tank that has moved can strain its gas connection or vent. If the technician sees signs of movement, they'll check those connections as part of the visit.
Technicians who work on gas and propane ignition every week.
Why this is technician work
Please leave these alone
- Relighting the pilot or cycling the gas control
- Removing burner covers or the sealed combustion door
- Cleaning or clearing the flame arrestor or burner
- Any gas fitting, valve or connection
Keeping the area around the heater free of stored items and lint is helpful and safe.
How the technician fixes it
The technician confirms the gas supply, observes the ignition sequence, and inspects the pilot or igniter, flame sensor, burner, air intake and venting. They test the thermocouple or sensor signal, check whether the gas control is responding, and look for signs of poor combustion such as soot or scorching. Then they replace or clean the failed component, relight or restart the unit, and watch it through several heating cycles to confirm a clean, stable flame and proper draft.
What affects the cost
| Failed component | Relative cost |
|---|---|
| Thermocouple or flame sensor | Usually among the least costly gas repairs. |
| Pilot assembly or igniter | Moderate; depends on the model. |
| Clogged arrestor or dirty burner | Labor-led; varies with how the combustion chamber is accessed. |
| Gas control | One of the costlier tank parts; weighed against replacement on older units. |
| Tankless board or flame rod | Varies widely by brand and model. |
How long it takes
Common ignition repairs on standard tanks are often completed in one visit when the part is on hand. Gas controls and tankless components are more model-specific and sometimes need ordering. The technician will tell you what to expect before starting.
Tell us the make, the ignition type if you know it, and what you've heard or seen.
Pilot and ignition questions
The most common reason is a worn or dirty thermocouple or flame sensor, which tells the gas control that a flame is present. If it can't sense the flame, the control shuts the gas off. A dirty pilot, a draft, a clogged flame arrestor on sealed-combustion models or a failing gas control can cause the same symptom.
We don't give relighting or ignition instructions on this site. If a pilot has gone out, something usually caused it, and relighting without finding the cause often just repeats the problem. A technician can relight it safely and check why it went out. If you smell gas, leave the building and call your gas utility and 911 from outside.
No. A delayed ignition, where gas builds up before it lights, is a sign something needs attention, such as a dirty burner, a weak igniter or a draft or venting problem. Don't keep using it and hoping. Call and describe it; it's worth having the burner and venting checked promptly.
Many modern gas tanks have a sealed combustion chamber with a screen or arrestor where air enters at the base. It's designed to keep flammable vapors outside the chamber from reaching the flame. In garages it can clog with dust and lint, starving the burner of air so the pilot or burner goes out. Cleaning or clearing it is technician work.
A lazy, yellow or sooty flame usually means incomplete combustion: not enough air, a dirty burner, or a venting problem. It can produce soot and is worth having checked soon. Keep the area around the heater clear, and call. If anyone has headaches or feels unwell near the heater, leave the building and call 911 from outside.
Clicking usually means the igniter is trying to light the burner but the unit isn't confirming a flame. Causes include a worn igniter or flame rod, a gas supply issue, a venting or air-intake problem, or a fault code the unit has logged. Note any code on the display and give it to us when you call.
It's possible. If other gas appliances aren't working either, the supply to the house may be the problem, and your gas utility or propane supplier is the first call. If other appliances work normally, the fault is more likely in the heater itself.
It's one of the costlier parts on a gas tank, and on an older tank the technician may suggest weighing it against replacement. On a younger tank that's otherwise sound, replacing the control is often the sensible repair. You'll get the price of both options before deciding.