How much does it typically cost to repair a generator?

Most standby generator repairs run about $150 to $600 in parts and labor on top of a typical $75 to $250 diagnostic fee, with the national average repair bill landing near $270. Portable-generator jobs like a carburetor cleaning or a recoil-starter fix are usually cheaper, often $50 to $600. A handful of jobs — alternator/stator winding repair, a full transfer switch installation, or a control board swap — commonly run $600 to $2,500 or more.

Is it cheaper to repair or replace a generator?

As a rule of thumb, if a single repair (or the total of recent repairs) reaches roughly half or more of what a comparable new generator would cost installed, replacement is usually the better value, especially on units past about 15 years old or ones needing repeat repairs within a year or two.

How Much Does Generator Repair Cost?

National ranges for the repairs behind the most common standby and portable generator fault codes, what pushes a job to the high or low end, and when it's smarter to replace the unit instead of fixing it again.

How these ranges are built

These are broad U.S. ranges pulled from contractor-rate cost aggregators that compile homeowner-reported job costs and repair-company rate sheets (Angi, HomeGuide), plus small-engine and generator repair shop cost guides for portable-unit jobs like carburetor and recoil-starter work. They are not a manufacturer price list and not a quote from this site — they're third-party estimates, cross-checked against multiple sources current as of August 2026 before publishing. The ranges are kept wide on purpose: parts pricing, regional labor rates, whether a shop charges a flat rate or hourly, and whether a job is DIY-adjacent or requires an electrician all move the real number a lot from job to job. Always get a local written quote before authorizing work.

Typical repair costs by job

Repair	Typical range	Notes
Diagnostic / service call fee	$75–$250	Many shops credit this toward the repair if you proceed
Starting battery replacement	$200–$500 installed	The single most common standby-generator fix
Spark plug / ignition service	$75–$250	Parts are cheap; the cost is mostly labor and access
Carburetor cleaning or rebuild (portable units)	$100–$600	A full carburetor replacement runs toward the top of this range
Recoil starter repair (portable units)	$50–$150	Parts alone are often under $60; replacing the assembly beats rebuilding it
Oil pressure switch / sensor replacement	$150–$400	A low oil level itself is a free top-off, not a repair cost
Voltage regulator (AVR) replacement	$300–$900	Common cause of both over- and under-voltage shutdowns
Transfer switch swap (like-for-like)	$400–$1,200 installed	Replacing an existing switch with the same type and amperage
New transfer switch installation	$1,200–$2,500+	Includes panel work; automatic switches and higher amperage push this up
Control board / PC board replacement	$600–$1,500	Board parts alone commonly run $400–$900 depending on model
Alternator / stator winding repair or replacement	$800–$2,500+	One of the most expensive common repairs
Cooling system repair (hoses, thermostat, radiator)	$150–$1,000+	Liquid-cooled units only; a full radiator swap lands at the top
Annual maintenance (oil, filters, plugs, battery test)	$200–$650/year	Not a repair, but skipping it is what leads to a lot of these

Matching a fault code to a likely repair

The fault code narrows down which row in the table above actually applies. A few of the most common patterns:

Won't start / overcrank (Generac 1100, Kohler Over Crank, B&S FC_4) — usually fuel, battery, or ignition. Often free to fix (open a valve, tighten a terminal) up through a $200–$500 battery or spark-plug job.
Low oil pressure shutdown (Generac 1300, Kohler Engine Oil Pressure Low, B&S FC_2) — an oil top-off is free; a failed pressure switch is $150–$400.
Low battery / charger warning (Generac Low Battery, Generac Charger Warning, Kohler Battery Voltage Low, B&S FC_1) — a new battery is $200–$500 installed; a dead onboard charger board runs closer to $150–$400.
Over/undervoltage (Generac 1800, Generac 1900, Kohler Voltage High, Kohler Voltage Low, B&S FC_3) — an AVR replacement is $300–$900; actual alternator or stator winding damage is $800–$2,500+.
Overspeed (Generac 1200, Kohler EngineSpeed High, B&S FC_6) — governor or throttle-linkage repair, typically $150–$600.
High temperature / coolant (Generac 1400, Kohler High Engine Temperature, Kohler Low Coolant Level, B&S FC_7) — often a $0 debris-clearing fix; a real cooling-system repair is $150–$1,000+.
Overload / transfer switch fault (Generac 2100, B&S FC_8) — load-shedding reconfiguration is mostly labor ($150–$400); an actual transfer switch repair runs $400–$2,500 depending on scope.

Full list: Generac codes, Kohler codes, Briggs & Stratton codes, or search the code lookup.

Repair or replace?

Two rules of thumb come up across the industry, and either one alone is a reasonable trigger to at least price out a new unit before paying for another repair:

The 50% guideline. If a single repair — or the running total of recent repairs — reaches roughly half or more of what a comparable new generator would cost installed, most service companies recommend replacing rather than repairing.
Age and repeat failures. Repair frequency tends to climb once a unit passes about 15 years old, and parts for older or discontinued product lines can take weeks to source. Needing a second unrelated repair within a year or two of the last one is a common sign the generator is nearing the end of its useful life rather than just having bad luck.

Warranty status overrides both of these — if the repair is covered under a manufacturer or extended warranty, repairing is almost always the right call regardless of the math above. Confirm coverage before you agree to pay out of pocket.

Before you authorize any repair: get an itemized, written quote — a single "parts and labor" number with no breakdown is a red flag. Confirm warranty status first, since many of the repairs above may be fully or partially covered. And treat any quote for transfer switch, alternator, or fuel-system work as electrical or gas-appliance work, not a handyman job — it should come from someone licensed to do it.

Before you touch anything yourself.

Standby generators run on LP or natural gas and carry mains-voltage output; portable generators carry mains-voltage output and burn gasoline. Fuel-line work, transfer-switch wiring, and anything inside the alternator housing should be done or verified by someone licensed to do it.
Never run a generator, or work on one, inside a garage or other enclosed space — carbon monoxide from the exhaust is fatal and has no smell.
If a repair estimate seems to be climbing because of vague "we're not sure yet" line items, ask for the specific failed part before approving more labor hours.

Sources

This site is an independent reference and is not affiliated with, endorsed by, or sponsored by any generator manufacturer. It is not a substitute for a licensed electrician or generator technician, and none of the figures above are a quote — get a local written estimate before paying for any repair. Standby and portable generators involve mains-voltage output and, on LP/NG units, a live fuel-gas supply; work on wiring, the transfer switch, or the fuel system should be done or verified by someone qualified to do it. Pages are written with AI assistance from the sources listed on each page and checked against them before publishing.