A gas smell or a changed flame
PG&E says to leave the area and call 911, then PG&E at 1-800-743-5000, and not to flip an electric switch on or off while you suspect a leak. The smell is sulfur-like, like rotten eggs. SoCalGas asks you to evacuate and call its own line, 1-800-427-2200, from a safe place.
For a pilot light that's out, PG&E's instruction is to shut the gas off at the appliance's shutoff valve and wait five minutes. SDG&E warns that a soft yellow flame can indicate carbon monoxide. Its advice is not to use an affected appliance until a qualified, licensed professional confirms it's safe.
Furnace repair prices in California, by scope
A diagnostic visit plus a small part, such as an igniter, flame sensor or switch, is estimated at $125 to $640. The figure moves to $235 to $1,525 for a control board, gas valve or draft inducer motor, and to $580 to $2,900 for a heat exchanger. Each is modeled from national published ranges adjusted by California's technician wage ratio of 1.16, so they're estimates, not quotes. Get a heat exchanger finding in writing, and have a second company check it.
| Item | Figure | What it is |
|---|---|---|
| Estimated range, diagnostic and minor part, not a quote | $125 to $640 per repair, diagnostic or minor part | A diagnostic visit and a small part such as an igniter, flame sensor or switch. Built from one national published range, adjusted by the California HVAC technician wage ratio (1.16). Basis: no state company sample (one counted California company price for this job), national estimate only. |
| Estimated range, major component, not a quote | $235 to $1,525 per repair, major component | A control board, gas valve or draft inducer motor, with the diagnosis that finds it. Built from 3 national published ranges, adjusted by the California HVAC technician wage ratio (1.16). Basis: no state company sample (no counted California company price for this job), national estimate only. |
| Estimated range, heat exchanger, not a quote | $580 to $2,900 per repair, heat exchanger | A cracked or failed heat exchanger. Built from 3 national published ranges, adjusted by the California HVAC technician wage ratio (1.16). Basis: no state company sample (no counted California company price for this job), national estimate only. |
| Technician wage, California mean | $36.24 an hour | BLS May 2025: what a technician earns, not a price you pay. |
Estimated ranges, with a row for each scope of work. Built from national published ranges (4 sources in all, 1 to 3 per row), adjusted by California's HVAC technician wage ratio to the US (1.16, BLS May 2025), plus the local permit fee where the city publishes one. Not a quote. Fifteen California HVAC companies publish a regular price for some HVAC service, but only one publishes a repair or installation price we could count, which is too few to show a range. Full method. Prices as of Oct 23, 2026.
When a repair bill makes you look at a new furnace
A new furnace brings a permit, a C-20 installer and, in the South Coast and Bay Area air districts, a nitrogen-oxide limit on gas furnaces; see furnace replacement for each. If the diagnosis is a heat exchanger, price a replacement before you approve the repair, using the estimates in the table above.
- The company names the failed part and shows it to you.
- The diagnosis is a failed heat exchanger, and a second company agrees in writing.
- The repair estimate keeps climbing toward the cost of a replacement.
Which license a furnace repair takes
CSLB's C-20 class covers fabricating, installing, maintaining, servicing and repairing warm-air heating systems, along with the ducts, registers, flues, thermostatic controls and air filters connected to them. Your furnace company should hold it. Put the license number into CSLB's license check, which lists the status and any complaint disclosure.
B&P 7048, as amended for 2026, exempts work on one project priced under $1,000 that needs no building permit. Anyone who advertises as a contractor or hires help to do the work loses it, so ask for the license number anyway.
The repair contract: the $750 line and the cancel window
CSLB calls the service and repair contract the main exception to the three-day right to cancel. It covers emergency repairs you request on short notice, it has to say it's a service and repair agreement, and labor and materials together must come to under $750. For most customers the right ends once the contract is signed and work begins.
Outside that exception, B&P 7159 requires a home improvement contract over $500 to be in writing with a three-day cancel notice. If you're 65 or older you get five days on either kind of contract. B&P 7159.5 caps the down payment at $1,000 or 10 percent of the price, whichever is less.
When a furnace problem can't wait for an appointment
- You smell gas: walk out, then phone 911 and your gas utility from a safe spot.
- A carbon monoxide alarm is sounding, or people in the house have sudden headaches, nausea or drowsiness: get outside, call 911 and keep everyone out until it's cleared.
- Something has damaged a gas line or meter, whether or not you can smell it.
- The furnace heats but has turned noisy, and there's no smell and no alarm: book a visit and jot down when the noise happens.
Three checks before you phone anyone
- Set the thermostat to heat, a few degrees above the room temperature, and put in fresh batteries if it takes them.
- Look at the filter; if it's choked with dust, replace it.
- If a gas pilot has gone out, turn the gas off at the appliance valve and wait five minutes as PG&E advises, and leave the house if you smell gas at any point.
Does a furnace repair need a permit in California?
San Diego's permit page says repair alone of a mechanical system needs no permit, while Los Angeles requires one for any installation or modification of a heating system. CSLB's letter to C-20 contractors puts a change-out that includes the furnace, air handler, coil or condenser on the permit list. A part swap is therefore a question for your building department, and a new furnace is a permit job.
Before any work starts, get the license number and check it with your state's licensing board; our state pages link the lookup.
Questions people ask
Do I need a license to repair a furnace in California?
A C-20 contractor license, with a narrow exception for casual work under $1,000 that needs no permit. CSLB's C-20 class is the one for warm-air heating systems, and servicing and repairing them is in its text. The $1,000 exemption in B&P 7048 only holds when the job needs no building permit, and it's lost if the person advertises as a contractor or employs anyone to do the work. Check the number on CSLB's lookup.
What does a furnace repair cost in California?
We estimate $125 to $640 for a diagnostic visit and a small part, and that's a model, not a quote. National published ranges, adjusted for California technician pay, set the figure, since one counted California company price is too few to replace it. Ask what the visit fee covers, and get the repair price in writing before work starts.
Can I cancel a furnace repair contract?
A home improvement contract over $500 carries a three-business-day cancel notice, but an emergency service and repair contract under $750 loses that right once you sign and work begins. The service and repair exception needs a contract that says so and a total under $750. Customers 65 and older have five days to cancel either kind of contract, under rules in force since 2021.
How much can a company ask me to pay up front?
Up to $1,000 or 10 percent of the contract, whichever amount is smaller. That cap is in B&P 7159.5, and CSLB repeats it on its consumer page. The one exception it names is a contractor with a Blanket Performance and Payment Bond on file, which CSLB says covers only about two dozen companies, and payments after the deposit can't run ahead of the work done.
Is a yearly furnace service required?
PG&E advises it and SDG&E recommends an annual safety checkup; nothing we cite makes it a legal requirement. PG&E's gas safety page says to have your furnace serviced once a year, and SDG&E's carbon monoxide page advises a yearly safety checkup. Treat both as safety advice, and ask a C-20 company what its visit covers.
- U.S. Bureau of Labor Statistics, OEWS May 2025: Heating, Air Conditioning, and Refrigeration Mechanics and Installers (SOC 49-9021), California, mean hourly wage Read Oct 23, 2026.
- U.S. Bureau of Labor Statistics, OEWS May 2025: Heating, Air Conditioning, and Refrigeration Mechanics and Installers (SOC 49-9021), United States, mean hourly wage Read Oct 23, 2026.
- HVACMatch: how we estimate costs, California (editorial policy) Read Oct 23, 2026.
- Gas Safety | PG&E Read Oct 20, 2026.
- Emergency Information | SoCalGas Read Oct 20, 2026.
- Carbon monoxide | San Diego Gas & Electric Read Oct 20, 2026.
- Gas safety | San Diego Gas & Electric Read Oct 20, 2026.
- Carbon Monoxide | SoCalGas Read Oct 20, 2026.
- City of Long Beach Contact Phone Numbers Read Oct 20, 2026.
- CSLB: Licensing Classifications Detail, C-20 Read Oct 20, 2026.
- CSLB: Check a License Read Oct 20, 2026.
- California Legislative Information: BPC 7048 Read Oct 20, 2026.
- CSLB: Learn About Home Improvement Contracts, Step 2 Warnings and Exceptions Read Oct 20, 2026.
- California Legislative Information: BPC 7159 Read Oct 20, 2026.
- California Legislative Information: BPC 7159.5 Read Oct 20, 2026.
- CSLB: What Should I Look for in a Contract and Binding Agreements? Read Oct 20, 2026.
- CSLB: C-20 Permit Enforcement Letter (PDF, 2010) Read Oct 20, 2026.
- CSLB: Do I need a building permit for my project? Read Oct 20, 2026.
- City of San Diego DSD: What Permits Do I Need? Read Oct 20, 2026.
- LADBS: Mechanical HVAC Permits Read Oct 20, 2026.
- South Coast AQMD: Rule 1111 (PDF) Read Oct 20, 2026.
- Federal Register 2024-27518 (Nov 29, 2024): BAAQMD Rules 9-4 and 9-6 Read Oct 20, 2026.