Generator silent during outage? Common causes.
When a standby generator fails to start during an outage — when you need it most — the cause is usually mundane. Battery, fuel, control board, or transfer switch issue.
By Steven Lockhart · Reviewed by Alex Towery, C-10 #989290
Updated 2026-06-16
Standby generator won't start during outage: (1) Check battery — most common single cause of starting failure (50%+ of no-start scenarios). Generator batteries die from neglect; if you haven't replaced yours in 3+ years, that's likely the cause. (2) Check fuel — natural gas supply (utility) and propane tank level. (3) Check control panel for fault codes. (4) Listen for any cranking sound — cranks but won't fire vs no sound at all are different diagnostics. (5) Call electrician for emergency dispatch if you can't restore. We carry replacement batteries and common parts for same-visit repair when possible.
01Top causes of standby generator no-start.
Generators that don't start during outages almost always failed for one of a small list of reasons: battery dead (most common — generator batteries need replacement every 3-5 years and most owners don't track it); fuel supply interrupted (natural gas pressure dropped during widespread outage, propane tank ran low or valve closed); control board issue (electronic fault, sometimes related to power-quality events during outage onset); transfer switch issue (failed to signal generator start, or signal failed to engage starter); generator just hasn't been exercised (sat without running for months — fuel system, starter, or oil pump issues accumulate).
Why batteries are the #1 cause: generators run their starter from a small lead-acid battery that's normally maintained by a trickle charger when the generator is in standby mode. Batteries degrade with age regardless of use, and the small trickle charger doesn't equalize plates the way a full charge cycle does. Result: batteries that test 'okay' in static measurement actually fail under starter load. A 3+ year old generator battery is suspect; 5+ year old battery is almost guaranteed to fail at the worst time. Replacement: $150-$300 typical.
02Diagnostic path when emergency dispatch arrives.
Battery test under load
First diagnostic step. Load test (not just voltage measurement) reveals batteries that look fine but can't deliver starting current. Replacement batteries carried for major brands (Generac, Kohler, Cummins, Briggs). If battery is the issue: replace, test start, verify normal operation.
Fuel supply verification
Natural gas: verify pressure at generator inlet (sometimes drops during widespread outages if utility regulator stations are affected). Propane: verify tank level, valve open, regulator function, supply line. LPG gauge can read 'full' but be inaccurate; check actual.
Control system diagnostic
Fault codes on control panel point to specific subsystems. Common codes: low coolant, low oil, overspeed, undervoltage, communication fault with transfer switch. Diagnostic per manufacturer service procedure. Some faults are quick reset; some require parts.
03Cost and aftermath.
Emergency dispatch cost: $300-$500 service call fee plus parts and labor. Most no-start scenarios resolve same-visit: battery $150-$300 + service call; fuel issue (utility) requires waiting on utility response but generator itself is fine; control board fault sometimes resolves with reset, sometimes needs parts ($200-$800+ depending on board). Total resolved-emergency cost typically $400-$900 for the common scenarios.
Aftermath: schedule annual generator service if you haven't been doing it. Most generator failures are preventable — annual service includes battery test/replace as needed, fuel system check, oil and filter change, exercise run, transfer switch test. Cost $250-$450 annually depending on size. The cost of one missed outage scenario (refrigerator contents lost, hotel stays, etc.) often exceeds 5 years of preventive service. Generator brand service contracts available through Towery for Generac, Kohler, and most major brands.
Common questions.
Why didn't my weekly exercise cycle prevent this?
Weekly exercise (the auto-run that most generators perform for ~10-20 minutes weekly) does some good — it confirms the generator can start and run briefly, lubricates components, identifies some failures early. But it doesn't load-test the system, doesn't fully cycle the battery, and doesn't reveal degradation that only shows under sustained outage conditions. Annual full service (load test, battery test, full diagnostics) catches what weekly exercise misses.
Should I try to start the generator manually?
If your generator has a manual start option (most do): yes, you can try. Open the control panel, switch to manual mode (per your generator's manual), attempt manual start. If it cranks but doesn't fire: fuel or ignition issue. If it doesn't crank: battery or starter issue. Don't keep cranking if it doesn't start within 10-15 seconds — you can flood it or damage the starter. After 2-3 unsuccessful attempts, wait for electrician.
Is generator failure during outage covered by warranty?
Depends on age and warranty terms. New generators (under 5 years) often have parts warranty that covers control boards, alternators, and major components. Labor coverage varies; often limited to first 1-2 years. Batteries are typically excluded as wear items. Service calls during emergencies are typically not warranty-covered. Check your specific warranty and consider extended coverage if generator is older.
How long can I wait for repair if no-start happens?
Emergency dispatch priority depends on circumstances. Medical needs (CPAP, oxygen concentrator, dialysis equipment), vulnerable occupants, or extreme weather: same-day priority. Inconvenience without urgent need: next-business-day acceptable. We triage emergency generator calls based on circumstances and dispatch accordingly. During widespread storm events, response queue extends; prioritize calling early when outage begins rather than waiting hours to see if it resolves.
How do you handle pricing — flat fee or hourly?
Both, depending on scope. Routine service calls and predictable scope (panel replacement, EV charger install, transfer switch install, fixture replacement) are flat-fee quoted up front. Diagnostic visits and emergency scope are hourly because we don't know what we'll find. Either way, you get a written quote before work starts on anything significant, and we don't proceed beyond the quote without your sign-off.
How quickly can you schedule?
Depends on scope and season. Emergency dispatch: same-day across Marin County (1-3 hours business hours, 1-4 hours after-hours). Same-day standard service: 3-6 hours from call when capacity allows; otherwise next business day. Scheduled service work: 1-3 weeks typical. Larger projects requiring permits and PG&E coordination: 4-12 weeks depending on scope. We're upfront about timeline at the quote stage.
What warranty do you offer on work?
Our standard residential warranty: 2 years on labor, manufacturer warranty on parts (varies by product — typically 1-10 years). Major installs (panels, generators, EV chargers) often have longer manufacturer warranties (5-10 years). If there's an issue with our work in the warranty period, we come back and fix it at no cost. We also stand behind work past warranty — repeat customers and referrals matter more than a transactional fix.
Are you licensed and insured?
Yes. California State License Board C-10 Electrical Contractor #989290, in good standing. Carry general liability insurance and workers' compensation insurance as required by California law. Bondable on projects requiring it. Happy to provide proof of insurance to clients or property managers on request. License lookup: cslb.ca.gov.
Emergency response across Marin County.
Same-day dispatch for safety scenarios. Typical on-site time 1-3 hours weekday, 1-4 hours after-hours.