Quick Answer
Annual maintenance should cover: oil and filter change per manufacturer schedule, battery load test and terminal cleaning, spark plug or injector inspection, air filter check, fuel system inspection, functional transfer switch test under a simulated outage, verification that the weekly self-test is running and passing, and a visual inspection of the pad, clearance area, and fuel connections. Keep written records of every visit.
Key Takeaways
- 1Oil and filter change is the baseline — use the manufacturer's specified weight and change interval.
- 2Battery load test is critical — a battery can appear fine and still fail to deliver cranking amps when the generator needs to start.
- 3Transfer switch functional test under simulated outage verifies the whole system, not just the engine.
- 4Self-test schedule verification confirms the unit is exercising itself between service visits.
- 5Written records of each service visit support warranty claims and add value at resale.
- 6Schedule service before your peak outage season so any issue gets fixed before you need the unit.
Engine and fluids
Oil and filter change per the manufacturer's schedule, air filter inspection or replacement, and a check of coolant levels on liquid-cooled models.
Electrical and battery
Battery load test and terminal cleaning — batteries are one of the most common points of failure on a unit that otherwise looks fine. Spark plug or injector inspection depending on the engine type.
System-level checks
A functional test of the transfer switch under a simulated outage, confirmation the weekly self-test is running and passing, and a visual inspection of the pad, clearance area, and fuel connections for any signs of wear or damage.
Documentation
Keeping a record of each service visit — date, work performed, any parts replaced — is useful both for warranty compliance and for demonstrating maintenance history if you sell the home later. Many owners find remote monitoring apps helpful here, since they log run history and maintenance milestones automatically.
Timing the visit
Scheduling annual service before your region's peak outage season — before hurricane season, before winter storm season, depending on where you live — means any issue a technician finds gets fixed with time to spare, rather than discovered mid-outage when the unit is needed most.
Frequently asked questions
Sources
- NFPA 37 — Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines — Covers clearance, ventilation, and safety requirements for stationary standby generators.
What should you do next?
See how often your generator should be professionally serviced and what happens if you skip a visit.
Service Frequency Guide →