Pilot light out: what a fix costs

Fixing a pilot light that will not stay lit costs $150 to $600, and the most common outcome is a thermocouple at $150 to $300. A pilot assembly runs $200 to $400, a gas valve $300 to $600, and the diagnostic visit that identifies which one is $100 to $250. After-hours calls add $200 to $500 for the schedule, not for better work.

Two numbers, not one

Every pilot repair invoice is a visit plus a part. Separating them is how you tell a fair price from an inflated one.

• The visit: $100 to $250 for diagnosis, or $200 to $500 after hours.
• The part and labour: $50 to $400 depending on what failed.

A $280 invoice for a thermocouple is roughly a $120 diagnostic plus $160 of part and labour. A $580 invoice for a gas valve is the same diagnostic plus $460. Neither is unusual.

Cost by cause

The last row is not a part replacement. A pilot that blows out when the main burner lights has a draft problem, and the fix is inspection and correction of the flue, venting or combustion air.

Four worked estimates

Estimate one: thermocouple on a 15-year-old furnace. Diagnostic $120, thermocouple $160, total $280. This is the single most common pilot repair in the US.

Estimate two: dirty pilot with a weak flame. Diagnostic $120, orifice cleaned and pilot reassembled $90, total $210. No parts beyond a gasket.

Estimate three: pilot assembly replacement. Diagnostic $120, assembly $280, total $400. The whole burner and pilot bracket is replaced, usually because the orifice is corroded into the assembly.

Estimate four: gas valve. Diagnostic $120, valve and labour $460, total $580. A leak test after installation is part of the job and should be on the invoice.

What drives the price

Access. A pilot assembly at the front of an open burner compartment is quick. One behind a sealed combustion chamber or in a tight closet takes longer.

Parts availability. Standing-pilot furnaces are old, and some parts are discontinued. A universal thermocouple is cheap and available; a model-specific pilot assembly may take a week and cost more.

Diagnosis time. A thermocouple is a two-minute test with a millivolt meter. A draft problem can take an hour of measurement.

Time of year. The first cold snap fills every service queue. Emergency pricing at $200 to $500 applies at nights, weekends and holidays.

Whether the diagnostic is credited. Some companies credit the $100 to $250 against the repair. That changes the effective repair price by up to $250, and it is worth asking on the phone.

The repair-or-replace arithmetic

A standing-pilot furnace is at least 20 years old, so the comparison is not close for anything beyond a single cheap repair.

On paper the repairs always look cheaper. The comparison that matters is not cost per year but expected remaining life.

A 25-year-old furnace with a $580 valve repair may run another three years or another ten. If it fails again next season, the two repairs total $1,160 against a $3,000 to $8,000 replacement, and the old unit still has a 65 to 70 percent efficient heat exchanger.

That is why the honest advice is: repair a thermocouple, and price replacement when the second significant fault appears in two seasons.

The full replacement range is in how much furnace repair costs, and the efficiency case is set out in is furnace repair worth it.

What the invoice should itemize

1. The diagnostic fee, and whether it is credited.
2. The part number and description.
3. The test performed — millivolt reading, gas pressure, or draft measurement.
4. A leak test after any gas-side work.
5. Labour, separately from the part where possible.
6. The warranty on the part and on the labour.

The third item is the one that separates a diagnosis from a guess. A thermocouple replaced without a millivolt reading is a part swap, not a repair.

When the number should stop you

A few quotes are worth refusing outright:

• $600 or more for a thermocouple alone. The part is inexpensive and the job is short.
• A gas valve replaced without a pressure test. That is a guess at the most expensive component.
• A pilot repair quoted without seeing the unit. The cause is not knowable by phone.
• A repair quote that exceeds a third of replacement cost on a unit over 15 years old, without a discussion of replacement.

For prevention, see pilot light out prevention, and for the symptoms that precede the failure, pilot light out warning signs. If the unit is a sealed-combustion model with electronic ignition rather than a pilot, the fault is different and no heat cost is the closer guide.

One final note on how to read a quote: ask whether the price assumes the pilot assembly comes apart cleanly. On an older furnace, the burner bracket and orifice are often corroded together, and what starts as a $210 clean becomes a $400 assembly replacement. A contractor who mentions that possibility before starting is being straight with you; one who discovers it afterwards and presents a larger invoice without a call is not.