Generac MGG350N2 troubleshooting: 17 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Generac MGG350N2 — full specs, parts & maintenance.
| Symptom | Cause | Remedy |
|---|---|---|
| Engine Cranks But Will Not Start | No fuel. Low oil level. Restricted air flow. No spark. | Check that fuel valves are open. Low Oil Pressure Shutdown activated. Replenish oil to full. Check/replace air filter. Check/replace spark plug(s). |
| Engine Will Not Crank (Electric Start) | Dead battery. Emergency stop is acti-activated. | Remove batteries and trickle charge. Never jump start. Even if only one battery is bad, it is recommended that both batteries be replaced at the same time. Reset controller after an emergency stop. |
| Engine Starts But Will Not Run Smoothly | Fuel or ignition problem. | Refer to engine manual. Contact Generac Mobile Products Technical Service. |
| Engine Overheats | Excessive load. Debris or dirt buildup on engine/radiator. | Remove one or more electrical loads. Remove debris. Clean engine surfaces to allow cooling. |
| No Output Voltage | Circuit breaker tripped or failed. Internal failure of alternator. | Reset circuit breaker or replace if required. Check electrical connections. Contact Generac Mobile Products Technical Service. |
| High Output Voltage | Excessive speed (fixed speed mode). | Check engine for malfunction. Verify engine RPM. |
| Electrical Shock When Frame Is Touched | Static charge. Grounded armature or field coil. | Ground unit frame at local reference ground. Contact service. |
| Mechanical Noise | Internal failure of alternator. Loose flexplate. Engine fan or belts issues. | Contact service. Tighten flexplate to flywheel and alternator shaft. |
| Controller Does Not Power Up Even With Correct DC Power Applied | Wiring mistake. Overload condition. | Check that there are no wiring errors/short circuits connected to the controller. Check breaker on the control panel. Check fuses on control panel. |
| LCD Display Cannot Be Viewed | Improper supply voltage. Improper contrast adjustment | Check DC supply voltage at terminals B+ & B- (10-30VDC). Adjust LCD contrast for best display. |
| Controller Cannot Be Reset | Engine not stopped. Controller not in OFF mode. | Verify the engine is at a complete stop before trying to reset. Set the controller to the OFF mode before trying to reset. |
| No 'RUN' Output Signal | 'Shutdown Faults' not reset. Engine speed not detected at cranking. | All shutdown faults must be reset (red shutdown LED must be off). Engine speed signal must be detected (speed signal green LED on) during cranking if the 'run-output fail safe' feature is enabled. Verify correct magnetic pickup signal at cranking (2.0VAC min. during cranking). |
| Overspeed Shutdown Occurs At Normal Speed | Controller programmed values are wrong or controller has failed. | Verify the controller programmed values are correct for the number of flywheel teeth, nominal RPM, |
| Voltage Or Current Metering Is Incorrect | Controller programmed values are wrong. Ground is missing. Voltage sensing wiring mistake. | Verify the controller programmed values are correct for the voltage sensing PT ratio and/or current sensing CT ratio. Verify that the battery supply DC negative conductor is properly grounded to the engine block (i.e. to a common ground point). Verify the voltage sensing wiring connection to the controller matches power distribution type. |
| Engine Temperature Or Oil Pressure Display Is Incorrect | Failed engine sensor. Ground is missing. | Verify engine sensors. Verify that the battery supply DC negative conductor is properly grounded to the engine block (i.e. to a common ground point). |
| Engine Alarms Are On For High Engine Temperature Or Low Oil Pressure When Engine Is Operating Properly | Wrong temp or pressure calibration. | Verify the engine mounted senders have correct resistance values for corresponding input temperature or pressure. Verify calibration. |
| Keypad Buttons (Switches) Do Not Operate | Keypad not connected to controller. | Verify the interconnecting ribbon cable between the lexan faceplate and main printed circuit board is correctly connected. Replace controller if failed. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: No fuel. Low oil level. Restricted air flow. No spark.. See the table for the matching fixes.
Documented causes: Dead battery. Emergency stop is acti-activated.. See the table for the matching fixes.
Documented causes: Fuel or ignition problem.. See the table for the matching fixes.