Generator Maintenance Checklist: What to Do Annually and Monthly

Published: January 17, 2025 | By Michael Davis, Generator Service Technician

Your home generator is like an insurance policy—you hope you never need it, but when you do, it needs to work perfectly. Regular maintenance is the key to ensuring your generator starts right up when the power goes out.

This straightforward guide breaks down exactly what you need to do to keep your generator in top shape, following recommendations from major manufacturers like Generac, Kohler, Briggs & Stratton, and Cummins. We've translated technical service manuals into simple steps that any homeowner can understand and follow.

Don't wait for an emergency! A well-maintained generator can last 2-3 times longer than a neglected one, saving you thousands of dollars and ensuring power when you need it most.

Monthly Generator Maintenance Tasks

All major generator manufacturers recommend these simple monthly checks to ensure reliability. These tasks take just 15-20 minutes but dramatically improve your generator's dependability.

Task	Description	DIY Friendly?
Run Test	Let your generator run for 10-15 minutes to ensure it starts properly and runs without issues	✓
Visual Inspection	Check for leaks, loose wires, rodent damage, debris around the unit	✓
Check Oil Level	Ensure oil level is at the recommended mark on the dipstick	✓
Check Coolant	For liquid-cooled models, check coolant level in the overflow tank	✓
Check Fuel Level	For propane/diesel models, check fuel level; for natural gas, verify valve is open	✓
Clear Debris	Remove leaves, grass, snow, or debris from around the generator	✓
Check Battery	Verify battery connections are tight and clean (no corrosion)	✓

Generac Models

Generac recommends using their Mobile Link™ app for automated reminders and to monitor your generator's status remotely.

Most Generac models run a 12-minute self-test weekly, but you should still perform a manual check monthly. On newer models (Guardian series), check the controller screen for any active alerts.

Kohler Models

Kohler recommends using their OnCue Plus system to receive alerts about your generator's status.

For Kohler models, pay special attention to the air intake, which may require more frequent cleaning in dusty environments. Their Decision-Maker controllers display maintenance reminders automatically.

Briggs & Stratton Models

Briggs & Stratton units with InfoHub™ will send maintenance alerts to your phone or email.

Their Fortress and Symphony II models have accessible maintenance points with color-coded caps, making monthly checks even easier for homeowners.

Cummins Models

Cummins recommends using their Connect Cloud service for automated maintenance tracking.

Their QuietConnect™ series has an easy-access door for simple monthly maintenance. Check the controller for "Maintenance Due" messages during your monthly inspection.

Pro Tip: Monthly Run Tests

Most newer generators automatically run weekly self-tests, but manufacturers still recommend a monthly manual run test under load.

How to do it:

Turn off your main utility power at the transfer switch
Let the generator power your home for 10-15 minutes
Return the transfer switch to utility power

This test confirms that the entire system—not just the generator engine—is working properly.

Annual Generator Maintenance Checklist

Annual maintenance is more comprehensive and usually requires a professional technician. All major manufacturers (Generac, Kohler, Briggs & Stratton, Cummins) require annual service to maintain your warranty. Here's what should be done each year:

Service Item	Description	Professional Only?
Oil & Filter Change	Replace oil and filter using manufacturer-recommended grade	Recommended
Air Filter Replacement	Replace air filter to ensure proper engine breathing	No
Spark Plug Service	Replace spark plugs (gas models) or check injectors (diesel)	Recommended
Battery Test & Service	Load test battery, clean terminals, check charging system	Yes
Fuel System Inspection	Check fuel lines, filters, and connections for leaks	Yes
Cooling System Service	Inspect radiator, clean fins, check coolant condition	Yes
Valve Adjustment	Check and adjust valve clearance if necessary	Yes
Transfer Switch Test	Verify transfer switch operation and connections	Yes
Control System Check	Verify all safety shutdowns and alerts function properly	Yes
Exhaust System Inspection	Check for leaks, corrosion, and proper attachment	Yes

Annual Service Costs

According to current manufacturer data and our dealer network, here are the typical costs for annual professional service:

Air-Cooled Home Generators (8-22kW)

$250 - $400 per year

Liquid-Cooled Home Generators (20-60kW)

$350 - $600 per year

Generac Maintenance Kits

$80 - $200 (DIY parts only)

Pre-Paid Maintenance Plans

$700 - $1,200 (3-year plans)

Note: Prices vary by region, generator size, and accessibility. Many dealers offer discounts for maintenance agreements.

DIY vs. Professional Maintenance: What You Should Know

What You Can Do Yourself

Monthly visual inspections
Checking fluid levels (oil, coolant)
Clearing debris from around the unit
Simple battery terminal cleaning
Air filter replacement (on most models)
Running exercise tests

Cost-saving potential: $100-$150 per year

When to Call a Professional

Annual comprehensive service
Any electrical system checks
Fuel system service and adjustments
Transfer switch testing
Battery load testing
Engine tune-ups and valve adjustments
Any service required by warranty

Typical service call duration: 1-2 hours

Important: Most generator warranties require annual professional maintenance. Skipping these services could void your warranty and leave you without coverage for major repairs.

Manufacturer-Specific Maintenance Requirements

While basic maintenance is similar across brands, each manufacturer has specific requirements to maintain warranty coverage:

Manufacturer	Required Service Interval	Special Requirements
Generac	Annual or every 200 hours	Requires Generac oil and filters for full warranty coverage; recommends service 6 months after initial installation
Kohler	Annual or every 100 hours	Specifies SN 5W-30 synthetic oil for most residential models; requires certified technician for warranty work
Briggs & Stratton	Annual or every 200 hours	Can use third-party service companies, but recommends authorized dealers; requires maintenance records
Cummins	Annual or every 150 hours	Emphasizes exhaust system inspections; requires registration of service in Cummins system for warranty

Generac PowerPact vs. Guardian Series: Maintenance Differences

PowerPact (8kW-11kW)

Oil change every 50 hours or annually
More frequent air filter checks
Manual exercise run required weekly
Annual service cost: $200-$300

Guardian Series (16kW-22kW)

Oil change every 200 hours or annually
Automatic weekly self-testing
Mobile Link™ compatible
Annual service cost: $300-$400

Seasonal Maintenance Considerations

Winter Preparation

Check battery condition (cold weather reduces capacity)
Verify block heater operation (if equipped)
For diesel units, use winter-grade fuel or additives
Clear snow after storms (maintain 3ft clearance)
Check antifreeze protection level (-20°F minimum)

Summer Preparation

Clean cooling fins/radiator thoroughly
Check exhaust system for nesting animals/insects
Verify air intake isn't blocked by vegetation
Consider increased cooling system inspections
Check generator load capacity (AC demands higher)

Finding Qualified Generator Service Technicians

For warranty-compliant service and the best maintenance experience, work with qualified technicians who specialize in your generator brand.

Service Type	Pros	Cons
Manufacturer-Authorized Dealer	Warranty-compliant service Factory-trained technicians Access to OEM parts	Typically higher service rates May have longer wait times
Independent Generator Service	Often more competitive pricing Potentially faster response times Multi-brand experience	May not maintain warranty Variable expertise levels
Maintenance Agreement	Priority scheduling Predictable annual costs Often includes discounted parts	Upfront multi-year commitment May include services you don't need

Questions to Ask a Service Provider

Are you factory-authorized for my generator brand?
Will this service maintain my manufacturer warranty?
Do you use OEM or aftermarket parts?
Do you offer emergency service outside business hours?
What's included in your standard maintenance package?
Can you provide documentation for warranty purposes?
Do you offer multi-year maintenance agreements at a discount?

Keeping Maintenance Records

Proper documentation is essential for warranty claims and can increase your generator's resale value. Keep these records:

Service Receipts

Keep all invoices showing dates, services performed, parts replaced, and technician information.

Maintenance Log

Record all maintenance including DIY checks, oil additions, and exercise run times.

Part Receipts

Save receipts for all parts and fluids used, especially if they're OEM certified.

Pro Tip: Digital Record Keeping

Many newer generators include digital maintenance tracking via smartphone apps:

Generac: Mobile Link™ ($0-$300 depending on model)
Kohler: OnCue Plus™ (included with most models)
Briggs & Stratton: InfoHub™ (subscription-based)
Cummins: Connect Cloud (included on newer models)

These systems track run hours, service intervals, and can even alert your service provider when maintenance is needed.

Money-Saving Maintenance Tips

Smart Ways to Save

Purchase multi-year maintenance plans (typical savings: 15-20%)
Schedule service in off-season months (many dealers offer discounts)
Perform simple monthly checks yourself
Replace air filters yourself (save $50-75 per year)
Join dealer loyalty programs for discounted parts
Keep your generator clean to prevent costlier repairs

What Not to Skip

Annual oil changes (even with minimal use)
Battery testing and maintenance
Transfer switch testing
Professional service required for warranty
Spark plug replacement at recommended intervals
Coolant services on liquid-cooled models

Remember: Skipping maintenance to save money often leads to much more expensive repairs later. A typical repair bill for a neglected generator can easily exceed $1,000-2,000, while annual maintenance costs only $250-400.

Warning Signs Your Generator Needs Immediate Attention

Don't wait for your scheduled maintenance if you notice any of these issues:

Unusual Noises

Grinding, knocking, or rattling sounds during operation could indicate serious engine problems.

Action: Shut down and call service immediately

Fluid Leaks

Oil, coolant, or fuel leaks around the generator base or connections require immediate attention.

Action: Call for service within 24 hours

Frequent Shutdowns

Generator starts but shuts down after running briefly, indicating safety system activation.

Action: Check error code and call service

Visible Smoke

Blue smoke (oil burning) or black smoke (improper fuel mixture) indicates serious issues.

Action: Shut down immediately and call for service

Failed Exercise Cycle

Generator fails to complete its weekly self-test or shows error codes afterward.

Action: Check controller screen and call service

Battery Alerts

Low battery alerts or failure to start during testing indicate electrical system problems.

Action: Schedule service within 48 hours

Common Generator Error Codes and Their Meaning

Modern generators display error codes to help diagnose problems. Here are the most common codes for popular models:

Brand & Code	Meaning	Typical Solution
Generac: 1500	Low Oil Pressure	Check oil level, check for leaks, possible oil sensor failure
Generac: 2800	Low Battery	Check battery connections, charge or replace battery
Kohler: E-1	Engine Speed Error	Possible throttle issue, requires professional service
Kohler: E-7	Overvoltage	Requires professional service, possible voltage regulator issue
Briggs & Stratton: 1-4	Low Fuel Pressure	Check fuel supply, possible fuel filter clog
Cummins: Code 359	Maintenance Due	Schedule regular maintenance service

For Complete Error Code Reference

Full error code lists are available in your owner's manual or online:

Generac: Download the Mobile Link app or visit their support website
Kohler: View error codes through OnCue Plus or on the generator controller
Briggs & Stratton: Access through the InfoHub portal or controller screen
Cummins: View on the digital display or Connect Cloud interface

Always have your generator model and serial number ready when discussing error codes with service providers.

Generator Service Plans: Are They Worth It?

Typical Plan Inclusions

Annual professional maintenance visits
Oil and filter changes
Air filter replacement
Spark plug replacement (when required)
Battery testing and maintenance
Priority emergency service
Discounted parts and labor

Average Cost: $250-500 per year

Is It Worth It?

Best for:

Homeowners who want predictable costs
Those who prefer "set it and forget it" maintenance
People in areas with frequent outages
Homes that rely on generators for medical equipment

May not be worth it if:

You're comfortable doing basic maintenance yourself
Your generator rarely runs
You plan to sell your home soon

Real-World Service Plan Costs

Generac PowerPro Dealer Plans

Basic Plan: $250-350/year (one annual visit)
Preferred Plan: $350-450/year (one annual visit + priority service)
Premium Plan: $450-650/year (semi-annual visits + priority service)

Kohler Authorized Dealer Plans

Standard Protection: $275-375/year
Complete Care: $375-475/year
Comprehensive: $475-575/year (including transfer switch service)

Note: Prices vary by region, generator size, and dealer. Many dealers offer multi-year discounts of 10-15% when prepaid.

Connect with Local Generator Service Pros

Find factory-authorized technicians in your area who can maintain your specific generator model. Our nationwide network includes certified professionals from all major brands.

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Your Generator Maintenance Calendar

Stay on track with this simple maintenance schedule:

Timeframe	Tasks to Complete
Monthly	Visual inspection Check oil level Verify automatic exercise completed Clear debris from unit Check for leaks or unusual conditions
Every 6 Months	Check battery terminals and clean if needed Inspect air filter (replace if dirty) Check coolant level (liquid-cooled models) Test manual transfer switch operation
Annually	Schedule professional service visit Complete oil and filter change Replace air filter Replace spark plugs (if due) Complete full system diagnostic test Test and service transfer switch
Every 2 Years	Replace battery (even if still working) Check valve clearance Replace coolant (liquid-cooled models) Inspect and clean fuel system
Every 3-5 Years	Replace fuel filter Replace radiator hoses (liquid-cooled models) Comprehensive fuel system cleaning Transfer switch major service

Maintenance Calendar Pro Tip

Set calendar reminders for your generator maintenance. Most manufacturers recommend:

Schedule annual service just before your area's typical outage season
For hurricane-prone areas: May-June is ideal for annual service
For winter storm regions: September-October works best
For wildfire-prone areas: Early spring before fire season

Quick DIY Maintenance Guide

Follow these step-by-step instructions for basic maintenance you can safely perform yourself:

Monthly Visual Inspection

Ensure generator is in "Auto" or "Ready" mode
Remove any debris, leaves, or snow from the enclosure
Inspect for signs of rodents or insects
Check for any oil, coolant, or fuel leaks under the unit
Ensure there's adequate clearance (3 feet) around the unit
Verify nothing is stored on or leaning against the generator
Check oil level using the dipstick (add if necessary)
Inspect coolant level in overflow tank (liquid-cooled models)
Check that all vents and air inlets are clear and unobstructed
Verify the exercise indicator shows recent operation

Time required: 10-15 minutes

Air Filter Check/Replacement

Ensure generator is off and disconnected from power
Locate the air filter compartment (typically behind a panel)
Remove the panel using a screwdriver if necessary
Remove the air filter carefully, noting its orientation
Hold the filter up to a light source - if light doesn't pass through, replace it
Install the new filter in the same orientation as the old one
Replace the cover and secure any fasteners
Restore generator to "Auto" mode when finished

Cost: $20-50 for replacement filter | Time required: 15-20 minutes

Battery Terminal Cleaning

Ensure generator is off and in manual mode
Remove the battery access panel
Identify positive (+) and negative (-) terminals
Check for white or greenish corrosion on terminals
If corroded, disconnect negative terminal first, then positive
Mix a solution of baking soda and water
Use an old toothbrush to clean terminals with the solution
Dry thoroughly with a clean cloth
Apply a thin coat of petroleum jelly or battery terminal protectant
Reconnect positive terminal first, then negative
Return generator to "Auto" mode

Time required: 20-30 minutes

Key Maintenance Takeaways

Monthly checks can prevent 70% of common generator problems
Professional annual service is critical for warranty maintenance
The average service cost of $250-400 per year is much cheaper than emergency repairs
Most major manufacturers (Generac, Kohler, Briggs & Stratton, Cummins) have similar maintenance requirements
Simple DIY maintenance can extend your generator's life, but doesn't replace professional service
Always follow manufacturer recommendations for oil, filters, and service intervals

Protect Your Generator Investment

Your home generator represents a significant investment in your family's comfort and safety. Regular maintenance ensures it will be ready when you need it most.

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