A pilot that lights and then goes out again is a safety system refusing to stay open — and it is usually right to.
A pilot light that lights and then goes straight back out is rarely a problem with the pilot itself. SAVA HVAC & Appliance Repair has serviced gas water heaters across Chicago and the North Shore since 2017, and in most cases the cause is the thermocouple — a safety device that must sense the pilot flame continuously in order to hold the gas valve open. As it ages it stops generating enough signal, the valve closes, and the pilot dies. A blocked pilot orifice produces the same result by starving the flame. So does a venting problem, because the safety system will shut the unit down rather than let combustion gases spill into the room. Every one of those is the heater protecting the household, which is why relighting it repeatedly does not fix anything. SAVA is EPA Section 608 Certified.
By far the most common cause. The thermocouple sits in the pilot flame and generates a small electrical signal that holds the gas valve open. It is proof to the valve that a flame exists. As the thermocouple ages that signal weakens, the valve interprets it as no flame, and shuts the gas off. The pilot then dies within seconds of being lit. It is a wear part and a routine replacement.
The pilot burns through a very small opening. Dust, lint, and combustion residue accumulate there and starve the flame of gas, producing a pilot that is weak, yellow, or unstable — which then fails to satisfy the thermocouple. Common in basements and utility rooms where the heater sits near a dryer or a workshop.
A gas water heater vents combustion gases up a flue. If the flue is obstructed, or downdraft is pushing exhaust back into the room, the safety system shuts the unit down. Newer heaters have a flammable vapour sensor and a spill switch that lock the unit out entirely. This is a safety shutdown, and the venting problem behind it needs correcting rather than bypassing.
The gas control valve houses the thermostat and the safety circuit. When the valve itself fails it may refuse to hold the pilot even with a perfectly good thermocouple. Diagnosis is a matter of testing the thermocouple output first, because replacing a valve is a considerably larger job than replacing the part that usually fails.
Water heaters need combustion air. A tightly sealed utility closet, a new exhaust fan, or a door that is now kept closed can all change the air available and produce a pilot that will not hold. It is a genuinely common cause after renovation work, and one that no amount of relighting will resolve.
Heaters built to FVIR standards include a sensor designed to shut the unit down if flammable vapours are present near the floor. Once tripped it needs a specific reset procedure, and it needs the reason it tripped identified — stored paint, solvents, or fuel near the heater is exactly what it exists to detect.
The more you can describe, the better the chance we arrive with the right part already on the truck. It helps to know:
Water heaters rarely recover on their own, and the failure modes get more expensive the longer they run. A tank that is corroding ends in a leak, sediment that is left in place shortens the life of the unit, and a safety device that keeps shutting the heater down is reporting a fault that has not been fixed.
SAVA is a family-owned, EPA Section 608 Certified company serving Chicago and the North Shore suburbs since 2017. We service gas, electric, and tankless water heaters, identify the exact fault before any work begins, explain what we found and what it will cost, and give straight repair-versus-replace guidance on older tanks. Learn more about our water heater repair service.
Plus most other residential tank and tankless water heater brands — if yours isn't on the list, call and we'll confirm.
Same-day service when available · Gas, electric & tankless · Chicago & North Shore
Same-day service available · $79 diagnostic — credited toward your repair · EPA Certified & insured