Generac MGG350N2 troubleshooting: 10 fault codes and 33 symptom-cause-remedy entries from the manufacturer's own service documentation.
Generac MGG350N2 — full specs, parts & maintenance.
| Code | Meaning | Cause | Remedy |
|---|---|---|---|
| ECU | Indication of error in communication with ECU | Check if the ECU is: correctly connected to the CAN1 port of the controller (refer to Comap Electronic Engines Support manual for information about ECU connection); powered up; terminating resistors are properly connected; the CAN bus Low and High wires are not swapped | |
| SHAinCfgErr | Shared Analog module configuration error | More than one source module (SHAOUT) were configured (on the CAN2 bus) | Make sure that only one SHAOUT x module is configured in controllers |
| ECUDiagBlocked | Alarm is active when Comms settings: ECU diag = DISABLED. This setting means that ECU alarms are not displayed and considered by controller and this alarm is the setting notification | ||
| Wrong config | Wrong controller configuration indication. Indicates that controller hardware doesn't support PLC used in configuration | To check it send the IDch and Dngl strings from controller Info screen 2 and archive to your technical support | |
| RTCbatteryFlat | This warning message "RTCbatteryFlat" appears in Alarmlist when battery is close to be completely flat | If power supply cut comes when the RTC battery is flat, the statistic values, history and setpoints settings are lost | Send a controller to your distributor for battery exchange if the RTCbatteryFlat message is displayed |
| Al/Hist. msg 1-16 | Al/Hist. msg 1-16 activity indication (Al/Hist. msg means Alarm/History message) | Al/Hist. msg can be used as a customized message for additional protection configured to any controller internal value. See GenConfig manual - Protections | |
| Batt volt | Indication of battery voltage protection activity | This protection is based on Analog protect: Batt >V, Batt <V, and Batt volt del setpoints | Check if engine alternator or independent battery charger works properly |
| EarthFaultCurr | Indication of Earth fault current protection activity | This protection is based on Gener protect: EarthFaultCurr and EthFltCurr del setpoints. Setpoint EarthFltCurrCT from Basic settings group of setpoints is related to this protection too | |
| Gen V unbal | Generator voltage unbalance alarm | Based on Gener protect: Gen V unbal and Gen V unb del setpoints. The voltage unbalance is calculated as a maximum difference between phase voltages | |
| Gen I unbal | Generator voltage unbalance alarm | Based on Gener protect: Gen V unbal and Gen V unb del setpoints |
| Symptom | Cause | Remedy |
|---|---|---|
| Engine Cranks But Will Not Start | No fuel | Check that fuel valves are open |
| Engine Cranks But Will Not Start | Low oil level | Low Oil Pressure Shutdown activated. Replenish oil to full |
| Engine Cranks But Will Not Start | Restricted air flow | Check/replace air filter |
| Engine Cranks But Will Not Start | No spark | Check/replace spark plug(s) |
| Engine Will Not Crank (Electric Start) | Dead battery | 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 |
| Engine Will Not Crank (Electric Start) | Emergency stop is activated | 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 | Remove one or more electrical loads |
| Engine Overheats | Debris or dirt buildup on engine/radiator | Remove debris. Clean engine surfaces to allow cooling |
| No Output Voltage | Circuit breaker tripped or failed | Reset circuit breaker or replace if required |
| No Output Voltage | Internal failure of alternator | 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 | Ground unit frame at local reference ground |
| Electrical Shock When Frame Is Touched | Grounded armature or field coil | Contact service |
| Mechanical Noise | Internal failure of alternator | Contact service |
| Mechanical Noise | Loose flexplate | Tighten flexplate to flywheel and alternator shaft |
| Mechanical Noise | Engine fan or belts issues | Contact Generac Power Products Technical Service |
| Controller Does Not Power Up Even With Correct DC Power Applied | Wiring mistake | Check that there are no wiring errors/short circuits connected to the controller |
| Controller Does Not Power Up Even With Correct DC Power Applied | Overload condition | Check breaker on the control panel. Check fuses on control panel |
| LCD Display Cannot Be Viewed | Improper supply voltage | Check DC supply voltage at terminals B+ & B- (10-30VDC) |
| LCD Display Cannot Be Viewed | Improper contrast adjustment | Adjust LCD contrast for best display |
| Controller Cannot Be "Reset" | Engine not stopped | Verify the engine is at a complete stop before trying to reset |
| Controller Cannot Be "Reset" | Controller not in OFF mode | Set the controller to the OFF mode before trying to reset |
| No "RUN" Output Signal | "Shutdown Faults" not reset | All shutdown faults must be reset (red shutdown LED must be off) |
| No "RUN" Output Signal | Engine speed not detected at cranking | 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, and overspeed set point percentage. Replace controller if failed |
| Voltage Or Current Metering Is Incorrect | Controller programmed values are wrong | Verify the controller programmed values are correct for the voltage sensing PT ratio and/or current sensing CT ratio |
| Voltage Or Current Metering Is Incorrect | Ground is missing | Verify that the battery supply DC negative conductor is properly grounded to the engine block (i.e. to a common ground point) |
| Voltage Or Current Metering Is Incorrect | Voltage sensing wiring mistake | Verify the voltage sensing wiring connection to the controller matches power distribution type. NOTE: Standard direct voltage connection requires that the generator's neutral is solidly grounded |
| Engine Temperature Or Oil Pressure Display Is Incorrect | Failed engine sensor | Verify engine sensors. NOTE: Engine sensors must be factory supplied units only |
| Engine Temperature Or Oil Pressure Display Is Incorrect | Ground is missing | 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: Internal failure of alternator; Loose flexplate; Engine fan or belts issues. See the table for the matching fixes.
Documented causes: Controller programmed values are wrong; Ground is missing; Voltage sensing wiring mistake. See the table for the matching fixes.