The four checks that cost nothing
This Old House's winter preparation guide works through these, and all four are things a homeowner can do:
| Check | What it is |
|---|---|
| The filter | dust collects during use; replacing it is the easiest way to keep the system performing |
| The pilot light | if it is out, relighting it may be as simple as a flame or pressing an ignitor button |
| The circuit breaker | the guide's own advice is to check the box before assuming the system needs repair or replacement |
| The thermostat | and never mounted near a fireplace, even an inoperable one, because the reading will be wrong |
Our reading, marked as ours. Two of those four are not furnace faults at all. A tripped breaker and a thermostat reading the heat of a fireplace are both situations where the furnace is working perfectly and has been told not to run. They cost nothing to rule out and they are the first things a technician will look at while the clock runs at Fixr's $87 to $162 per hour.
If it is a part, here is the floor
Fixr's guide puts the whole range at $349 to $650 for most repairs, with an average of $485. Its low end is $66 and its high end is $2,673.
The parts that stop a furnace starting at all are at the cheap end:
| Part | Cost including the service call |
|---|---|
| Limit switch | $66 to $122 |
| Flame sensor | $68 to $127 |
| Thermostat | $91 to $169 |
| Ignitor | $96 to $178 |
| Control board | $390 to $725 |
Our note: the control board is the outlier at $390 to $725, and it is the one failure on this list that can make a furnace do nothing at all with no other symptom. Everything above it is under $180 fitted.
If the furnace runs but the air coming out is cold, that is a different fault with a different short list, and our furnace blowing cold air page works through it.
The problem that is not the repair
This Old House names it, and it is the reason this page argues for a test run rather than a repair:
Of course, you could call an HVAC technician for an emergency house call but considering that others invariably have the same problem, you may not get help for quite [a while]
Every furnace in the neighbourhood is asked to start on the same cold morning, and every one that is going to fail fails then.
Its recommendation: turn the system on in the autumn and run it above the house temperature, to find the fault while the queue is short. The guide also tells you what to expect: a furnace fired for the first time in a season often smells a little, but anything smelling of burning plastic or electrical wiring needs an inspection.
Our reading, marked as ours. A test run in September costs nothing and converts an emergency call-out into a routine appointment. On this evidence it is the single highest-value habit in this whole section, and it is free.
What the preventive version costs
Bob Vila prices the annual tune-up that is meant to stop this happening:
| Fuel | Tune-up cost |
|---|---|
| Electric | $70 to $130 |
| Gas | $80 to $170 |
| Oil | $100 to $200 |
| Typical range, any fuel | $100 to $200 |
Bob Vila notes that labor makes up most of that cost, and that repairs found during a tune-up average $100 to $600 on top.
Our arithmetic, marked as ours. A tune-up at $150, in the middle of the band, against an average repair of $485 means the tune-up pays for itself if it prevents roughly one failure in three. We cannot tell you whether it does, because neither source quantifies how much maintenance reduces the chance of a breakdown, and we are not going to invent a figure. Our maintenance page sets out the same arithmetic for the whole system, and our lifespan page shows that the gap between the two publishers' expected lifespans is itself largely the maintained case against the un-maintained one.
What we can say is that the tune-up and the test run are different things. One is a professional visit at $100 to $200. The other is you turning the heating on in September, and it is free.
One saving worth taking while you are there
This Old House, citing its own magazine: setting the thermostat back 7 to 10 degrees for eight hours while you are out each day can shave up to 10 percent off the yearly heating bill.
Our note: that is a bigger number than most of the repairs on this page, repeated every year.
Before you call
- Check the breaker. It is free and it is the guide's own first suggestion before assuming a fault.
- Check the thermostat, including whether anything warm sits near it.
- Change the filter.
- Look for the pilot light or press the ignitor button if your furnace has one.
- If it smells of burning plastic or wiring, stop and call. That is not a DIY list item.
- Next September, run the heat for an hour before you need it. It is the cheapest insurance in this section.
Sources
- This Old House, How to Get Your Furnace Ready for Winter, updated June 8, 2026 (the autumn test run and why it matters, the filter, the pilot light and ignitor button, the circuit breaker, thermostat placement, and the setback saving)
- Fixr, Furnace Repair Cost, updated August 29, 2025 (the $485 average, the $66 low end, the part cost table including ignitor and control board, the hourly labor rate, and the signs needing attention)
- Bob Vila, How Much Does a Furnace Tune-Up Cost?, updated January 27, 2023 (the $100 to $200 tune-up, the figures by fuel type, and the $100 to $600 range for repairs found during a tune-up)
Price figures are national US ranges from the sources above as of the date shown. Your local price depends on labor rates, permits and site conditions. Read how we get our numbers.