When a home generator won’t start, the cause is a dead or weak battery far more often than a failed engine. That single part is behind most no-start calls in San Diego County, and it’s usually a cheap fix once someone confirms it. Home generator repair starts with a diagnosis, not a parts swap, and a licensed electrician can tell you in one visit whether you’re looking at a $250 battery or a control board.
TL;DR
- The most common reason a home generator won’t start is a dead or weak starting battery; replacement runs roughly $200 to $400 installed.
- Stale fuel, a closed gas valve, a controller left off “AUTO,” and a tripped main breaker are the next most frequent no-start causes, and several you can check yourself.
- A diagnostic service call in San Diego typically runs $100 to $200, credited toward the repair if you move forward.
- Control-board and transfer-switch repairs are the pricier failures, often $400 to $1,500 depending on the part.
- Coastal San Diego salt air corrodes battery terminals and connections faster, so units in La Jolla, Coronado, and Encinitas fail sooner without service.
Why won’t my home generator start?
A weak or dead battery is the answer most of the time. Standby generators sit idle for months between outages, and the starting battery quietly loses charge the whole time. When the grid finally drops, the unit tries to crank, the battery can’t turn it over, and you get clicking or nothing at all. Manufacturers like Generac, Kohler, and Cummins all rank battery failure as the top no-start cause on residential units. If your unit is a Generac, our Generac generator repair guide covers what its lights and alarms mean before you call.
After the battery, the usual suspects are fuel and controls. A natural-gas or propane unit needs its supply valve fully open, and a controller has to be set to “AUTO” to start on its own during an outage. If someone put it in “OFF” after the last service, it will never fire. A tripped main breaker or a fault on the automatic transfer switch will also block startup even when the engine is fine.
The most common generator failures, in order
Here’s what an electrician checks, roughly in the order these parts fail:
- Starting battery. Weak, discharged, or corroded. The number-one no-start cause. Batteries should be tested yearly and replaced every two to four years.
- Fuel supply. A closed gas valve, low propane tank, or stale gasoline in a portable unit. Old fuel gums up carburetors and injectors.
- Oil and air filters. A clogged air filter starves the engine, and low or dirty oil triggers a protective shutdown on many models.
- Controller setting. Left on “OFF” or “MANUAL” instead of “AUTO,” so the generator never senses the outage.
- Transfer switch or main breaker. A tripped breaker or a failed transfer switch stops power from reaching the house even when the engine runs.
- Corrosion and rodents. Salt-air corrosion on terminals and chewed wiring, both common in outdoor San Diego installs.
- Control board. The costliest common failure, and the one that needs a pro every time.
Regular generator maintenance prevents most items on this list. The units that strand homeowners during an outage are almost always the ones that skipped their annual service.
What you can safely check before calling for repair
A few checks are safe for any homeowner, and they’ll often get a unit running or at least tell the electrician where to start:
- Confirm the controller is on “AUTO.” This is the single most common oversight after a service visit.
- Check the main breaker on the generator and the transfer switch. Reset a tripped breaker once. If it trips again, stop and call.
- Make sure the fuel valve is open. For natural gas, the supply valve should be in line with the pipe. For propane, check the tank gauge.
- Look at the control panel for a fault or error code. Write it down before you clear it. Codes like “low oil” or “overcrank” tell the electrician a lot.
- Inspect the battery terminals for white or green corrosion. You can see it, but don’t start disconnecting cables.
Then stop. Never open the generator’s electrical enclosure, work on the transfer switch, or attempt internal engine or wiring repair yourself. Those carry a real shock and backfeed risk, and DIY work will void the manufacturer’s warranty. Anything past the checks above is a job for a licensed electrician. If the power is out and the generator still won’t run, that’s an electrical emergency, and same-day help is worth the call.
What home generator repair costs in San Diego
Repair cost depends entirely on which part failed. These are typical San Diego ranges for residential standby units:
- Diagnostic service call: $100 to $200, usually credited toward the repair if you approve the work.
- Battery replacement: $200 to $400 installed, the most common repair by far.
- Fuel system cleaning or valve repair: $150 to $500.
- Oil, filter, and spark plug service: $150 to $400, often bundled into an annual visit.
- Automatic transfer switch repair or replacement: $400 to $1,500 depending on the model.
- Control board replacement: $500 to $1,500, the priciest common failure.
This is different from a maintenance contract, which runs $300 to $600 a year and is meant to prevent these repairs in the first place. When you call Bright Pro Electric, a licensed electrician diagnoses the unit, gives you a flat repair price before touching anything, and tells you honestly whether a fix or a replacement is the smarter money.
Repair vs. replace: when a generator isn’t worth fixing
Age and repair cost decide this. A standby generator lasts 15 to 20 years with maintenance and 10 to 15 without. If a unit is past that window and the quote is a control board plus a battery plus fuel work, you’re spending half the cost of a new install on a machine near the end of its life.
The rule most electricians use: if a single repair runs more than half the price of a new unit, replacement usually wins. A newer generator comes with a fresh warranty, better fuel efficiency, and current transfer-switch technology. If you land here, our guide to whole-house generator installation walks through sizing, fuel, and permit costs so the replacement number is no surprise.
Coastal San Diego: why salt air shortens generator life
Generators installed near the coast fail sooner, and corrosion is why. Salt-laden air attacks battery terminals, control connections, and enclosure hardware on units in La Jolla, Coronado, Del Mar, and Encinitas. A connection that would last years inland can corrode enough to cause a no-start in a fraction of that time on the coast.
That’s the practical reason coastal homeowners see more no-start calls: the battery and its connections are the first thing salt air degrades, and the battery is already the top failure point. Twice-yearly terminal cleaning and a corrosion check on coastal installs pays for itself. It’s also why PSPS-season readiness matters here. The outage arrives when fire weather does, and that’s the worst possible moment to learn your battery gave out.
Frequently asked questions
Why does my home generator crank but not start?
Cranking means the battery is fine and the starter works, so the problem is usually fuel or ignition. Check that the gas or propane supply valve is fully open and the tank isn’t empty. Stale fuel in a portable unit, a clogged fuel line, or a fouled spark plug are the common culprits. If the fuel supply is confirmed and it still won’t fire, a licensed electrician should look at the ignition and fuel systems.
How much does home generator repair cost in San Diego?
Most repairs land between $200 and $600, with the battery being the most common and affordable fix at roughly $200 to $400 installed. A diagnostic service call runs $100 to $200 and is typically credited toward the repair. Larger jobs like a control board or transfer switch can reach $1,500. Bright Pro Electric gives you a flat repair price before any work starts.
Can I repair my standby generator myself?
You can safely check the battery terminals, the fuel valve, the controller setting, and the main breaker. Beyond that, no. Opening the electrical enclosure or working on the transfer switch carries a shock and backfeed risk, and DIY repairs void the manufacturer’s warranty. Anything internal should go to a licensed electrician.
How often should a generator be serviced to avoid repairs?
Once a year at minimum, plus a battery test. Annual service catches the dead battery, stale fuel, and clogged filters that cause most no-start failures. Coastal San Diego units benefit from a twice-yearly corrosion check on top of the annual visit.
My generator won’t start during an outage. What do I do first?
Confirm the controller is set to “AUTO,” check that the fuel valve is open, and reset the generator’s main breaker once. If it still won’t run and your power is out, call for emergency service rather than trying to open the unit. A generator that fails mid-outage almost always needs a battery or a control repair a pro can handle same-day.
Bright Pro Electric connects San Diego County homeowners with licensed, vetted electricians for generator repair, 24/7. If your standby won’t start, call (858) 988-5580 for a same-day diagnosis, or learn how generator installation and service keeps a unit from failing when the grid goes down.