Onan 3 fault code — Generator
Applies to: QG 4000/3600 LP KYD Spec A-C
What 3 means
The Cummins Onan QG 4000/3600 LP KYD operator manual lists Code 3 as Service Check.
Owner-safe checks
- Press Stop once to read the two-digit second-level blink code if the manual procedure is available.
- Record the full blink sequence and stop using the generator if the fault repeats.
Service-only work
- Internal generator electrical, fuel, engine, sensor, controller, and output-voltage diagnosis belongs to Cummins service or a qualified generator technician.
Safety boundary
Generators can produce carbon monoxide, moving-part hazards, fuel hazards, and lethal voltage. Shut the generator down and do not open energized compartments unless qualified.