Service B
Generac Generator
Severity: MinorWhat Does This Error Mean?
Generac Service B is the second annual maintenance reminder on the Evolution and Nexus controllers.
Where Service A is roughly an oil-and-filter check, Service B adds the air filter and spark plug inspection at a longer interval — typically 200-400 run hours or 2 years.
It is a notice, not a fault.
The generator continues to run.
The reset is in the controller's Edit menu.
Affected Models
- Generac Guardian 7-22 kW air-cooled
- Generac Guardian 24 kW
- Generac Protector liquid-cooled
- Generac Evolution controller models
- Generac Nexus controller models
Common Causes
- Run hours crossed the Service B interval
- Calendar timer reached the 2-year mark
- Counter never reset after the previous Service B
- Recent firmware update that reset the schedule
How to Fix It
-
Press Enter on the controller.
The Evolution display shows current run hours and which Service interval is due.
Note the value — useful for keeping records of when each service was performed. -
Change oil and oil filter.
Same as Service A.
Drain warm oil into a pan, spin off the filter, install new filter with a thin film of oil on the gasket, refill to dipstick mark with the correct weight (typically 5W-30 synthetic). -
Replace the air filter.
Open the housing and pull out the foam or paper element.
Inspect — heavily clogged or oil-soaked = replace.
Generac air filters are 15-30 USD.
This is the main item that distinguishes Service B from Service A. -
Inspect the spark plug.
Disconnect the plug wire.
Pull the plug with a spark plug socket.
Light tan colour on the porcelain = healthy.
Black soot, oil fouling, or eroded electrodes = replace.
Genuine Generac plugs are 8-15 USD. -
Check the battery and connections.
Clean any white or green corrosion at the battery terminals.
Confirm the battery is at full charge — Generac batteries should test above 12.6V at rest. -
Run an exercise cycle.
Manually start an exercise from the controller.
Listen for unusual sounds.
Confirm the generator transitions to running at rated frequency.
Stop after 10 minutes. -
Reset Service B.
On the Evolution controller, navigate to Edit then Reset Maintenance.
Choose Service B.
Confirm.
The reminder clears and the next-interval counter starts.
Frequently Asked Questions
Should I do Service A and Service B together?
Many owners batch them.
Doing both at the longer interval is fine as long as you do not skip the shorter Service A items.
If your generator runs many hours per year, the intervals diverge and they need to be done separately.