Short answer: a home standby generator needs a weekly self-test (automatic), a quick visual check monthly, and a full service annually or roughly every 200 run hours, whichever comes first. The annual service is oil, filters, plugs, battery, and a load test. Skipping it is the single most common reason generators fail during an outage.
Most generator failures we get called for were preventable. Not because the owner did anything wrong, but because a standby generator is easy to forget. It sits quietly for months and gives no indication that anything needs attention, right up until the night you need it.
Here is the full schedule, what each item is actually for, and what it costs you to skip.
The maintenance schedule at a glance
| Interval | What happens | Who does it |
|---|---|---|
| Weekly | Automatic self-test, 10–20 minutes | The generator, automatically |
| Monthly | Visual check, clear debris, confirm AUTO | You, two minutes |
| Annually or ~200 run hours | Oil, oil filter, air filter, plugs, battery test, load test | You or a technician |
| Every 3–5 years | Battery replacement | Technician, usually |
| Per manual | Coolant on liquid-cooled units | Technician |
| After any long outage | Treat as a service interval | Technician |
Weekly: the self-test
Your generator runs a self-test on a set schedule, usually weekly, for roughly ten to twenty minutes. You do not have to do anything. But you should know when it happens and roughly what it sounds like.
Why it matters more than people think. The self-test is your early warning system. If it stops happening, or the unit throws a fault during it, that is the generator telling you it would fail during a real outage. A failed self-test is not a minor annoyance. It is the notice period.
Two practical points. First, the test schedule is configurable, so if it is running at an inconvenient hour you can move it. Second, if you have genuinely never noticed it, go and check the controller. A generator that has not exercised in months is a generator with a stiff engine and a draining battery.
Monthly: the two-minute walk-around
This is the only part that requires anything of you, and it takes less time than checking the mail.
- Clear the airflow. Leaves, grass clippings, mulch, anything piled against the enclosure. A generator packed with debris runs hot, and heat is what kills engines.
- Look for nesting. Rodents, wasps, and fire ants all like the warm dry space inside a generator enclosure. Chewed wiring is a genuinely common failure cause in units that sit unused.
- Check the pad. Oil or coolant staining underneath means a leak that will not fix itself.
- Read the controller. No warnings, and the unit is in AUTO. That second one matters more than it sounds.
- Check clearances. Shrubs grow. What was a clear three feet at install can be a hedge two years later.
The AUTO check catches a surprisingly common problem: someone worked on the panel, the HVAC, or the generator itself, left the switch in OFF or MANUAL, and nobody noticed for months. In either position the generator will not start when the power goes out.
Annually: the real service
This is the one that gets skipped, and it is the one that matters. A typical annual service covers:
- Oil and oil filter. Oil degrades whether the engine runs or not. Old oil in a generator that suddenly runs eighteen hours straight is how engines get damaged.
- Air filter. Cheap, and a restricted filter makes the engine work harder for every hour it runs.
- Spark plugs. Worn plugs make starting harder, which is the exact moment you care most.
- Battery test and terminal cleaning. Corroded terminals cause no-starts that look like much bigger problems.
- Valve clearance on models that call for it.
- Load test. Running the unit under real electrical load rather than just letting it idle. This is what separates a service from an oil change.
Annual or by run hours?
Whichever arrives first. Most air-cooled residential units call for service around every 200 run hours, and the first oil change usually comes much earlier, often around 25 hours after installation. Intervals vary by model, so check your manual or ask us about your specific unit.
For most households that only run the generator during outages, the calendar gets there first. But after a hurricane season with two multi-day outages, run hours can get there faster than you expect. A generator that ran 60 hours in September has done real work.
Why the load test is the part that matters
An engine can start and idle beautifully and still fail the moment it is asked to carry a house. A load test also exercises the transfer switch, and a meaningful share of “my generator failed” calls turn out to be transfer switch problems rather than engine problems.
An oil change alone does not catch that. More on what the transfer switch does.
Every few years
- Battery replacement. Typically three to five years in this climate. Heat is harder on batteries than cold, and Houston-area summers are hard on them. Replace it on schedule rather than after it strands you.
- Coolant on liquid-cooled units, per the manufacturer interval.
- Fuel system inspection, particularly on propane, where regulators and connections deserve a look.
After any extended outage
If your generator ran continuously for more than a day or two, treat that as hitting a service interval regardless of what the calendar says. It burned oil, pulled a lot of air through the filter, and put real hours on the engine in a short window.
This is the maintenance most often missed, because the outage ends, the power comes back, and everyone moves on. Hurricane season checklist.
What skipping maintenance actually costs
Two things, and the second one is worse.
It shortens the life of the unit. Maintenance is the single biggest variable in how long a generator lasts, more than brand or model. More on lifespan.
It fails when you need it. A generator that has not been serviced does not fail gradually in a way you notice. It fails at hour six of a hurricane outage, in the dark, when no technician within fifty miles can get to you for three days.
That asymmetry is the whole argument. The cost of maintenance is predictable and small. The cost of failure is unpredictable and large.
Should you do it yourself?
The monthly walk-around is yours, always.
The annual service is a reasonable DIY job if you are comfortable with small engines and you buy the correct filters and plugs for your specific model. Plenty of capable owners do it.
The honest case for having it done: the load test and transfer switch check. Those need equipment and access most homeowners do not have, and they are where a real share of failures hide. If you DIY the oil and filters, consider still having a technician do a load test periodically.
Our maintenance and service options
Frequently asked questions
How often does a home generator need to be serviced?
Annually, or roughly every 200 run hours for most air-cooled residential units, whichever comes first. The first oil change is usually much earlier, often around 25 hours after installation.
What happens if I never service my generator?
It will likely still run its self-test for a long time, which is what makes this dangerous. The failure shows up under sustained load during an actual outage. Old oil, a clogged filter, worn plugs, and a dying battery compound.
How long does a generator battery last?
Typically three to five years in this climate. Heat shortens battery life, so Gulf Coast batteries generally do not last as long as the same battery further north.
Can I service the generator myself?
The monthly checks, yes. The annual oil and filter service, yes if you are comfortable with small engines and use the right parts. The load test and transfer switch inspection are worth having done professionally.
My generator failed its weekly test. Is that urgent?
Treat it as urgent. A failed self-test means it would very likely fail during a real outage. Troubleshooting guide or call us.
Do you service generators you did not install?
Yes. We service Generac home standby generators regardless of who installed them. We do not work on diesel units or anything over 150 kW.
Getting on a schedule
If you are not sure when your unit was last serviced, that is itself the answer. We service Generac generators throughout Montgomery, Waller, and Grimes counties and the greater Houston area, and we offer 24/7 emergency service when something goes wrong at the worst time.