The Magnum MMG120 is a 91 kW (91 kVA) diesel standby generator set powered by a John Deere PE4045HF285 engine. It is available at 120/240 V, 120/208 V and 277/480 V, single/three-phase and 60 Hz. It holds about 13.7 L (3.6 gal) of oil and 29.8 L (7.9 gal) of coolant, with a maximum ambient rating of 48.89 °C. Starting uses battery rated 1000 CCA. The set measures 3350×1270×1950 mm (131.9×50.0×76.8 in), weighs about 2463 kg (5430 lb) and produces 68 dBA at 7.01 m. An integrated tank holds 1294.6 L (342.0 gal), roughly 44 hours of runtime. The same PE4045HF285 engine also powers generator sets from Generac.
The Magnum MMG120 is rated 91 kW standby (91.0 kVA).
What engine does the Magnum MMG120 use?
The Magnum MMG120 is powered by the John Deere PE4045HF285 engine.
What fuel does the Magnum MMG120 use?
The Magnum MMG120 runs on diesel.
What is the oil capacity of the Magnum MMG120?
The John Deere PE4045HF285 engine in the Magnum MMG120 has an oil capacity of 13.7 liters.
Troubleshooting
8
Fault codes
Code
Meaning
SD
Sensor fail (FLS)
WRN
Warning (WRN)
Symptoms & remedies
Symptom
Cause
Remedy
LOW FUEL LEVEL SHUT DOWN
Fuel level on the Liquid Crystal Display (LCD) window is low or fuel tank has leaks.
Check the fuel level and ensure it is not running dry. Check for leaks in the fuel tank.
LOW OIL PRESSURE SHUT DOWN
Engine oil pressure is less than 20 psi (138 kPa).
Check engine oil level and add oil if required. Visually inspect the engine for oil leaks.
LOW COOLANT LEVEL SHUT DOWN
Coolant level in the radiator is low or coolant lines have visible leaks.
Check the coolant level and add coolant if necessary. Inspect for leaks in coolant hoses, engine block, and water pump.
HIGH COOLANT TEMPERATURE SHUT DOWN
Coolant temperature is 230°F (110°C) or more.
Check coolant level in the overflow jug and add coolant if necessary. Inspect radiator, coolant hoses, engine block, water pump for leaks. Check serpentine drive belt tension.
OVERCRANK SHUT DOWN
Engine will not start.
Check fuel level in tank and proper operation of the fuel pump. Check air filter for blockage.
OVERSPEED OR UNDERSPEED SHUT DOWN
Engine speed is above or below 60.0 Hz.
Disconnect all loads and restart the generator to read frequency (Hz). Adjust engine speed as necessary.
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.