Isuzu 4LE1NYGV-03 Engine

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Shared across brands: Generac, Magnum

• Mast Lights On But the Light Output is Low
  Cause: Fixture and/or lens is dirty.
  Fix: Clean reflective surface inside fixture and both inside and outside surface of glass lens. Use mild soap and water to clean lens. Other chemicals may have an adverse effect on the glass.
• Mast Lights Off, but Ballast Indicators on Control Panel are On.
  Cause: Light fixture is too hot.
  Fix: Allow light to cool 10-15 minutes before restarting.
• Low Oil Pressure Shutdown
  Cause: Engine oil level low; Oil leaks; Oil pressure sender faulty
  Fix: Check the level of the engine oil with the dipstick and add oil if required; Visually inspect the engine for oil leaks; If the oil level is good, restart the unit and verify the loss of oil pressure and shut the engine down immediately if the oil pressure value does not read 5 psi (34 kPa) within five seconds; Check the oil pressure sender and refer to the troubleshooting section of the engine operator's manual
• High Coolant Temperature Shutdown
  Cause: Coolant level low; Radiator shroud and ducting blocked; Visible leaks in coolant hoses, engine block or water pump; Serpentine drive belt for the water pump loose
  Fix: Check the coolant level in the overflow jug; Restart the engine and read the coolant temperature to verify High Coolant Temperature Shutdown and stop the engine immediately if the coolant temperature is 230°F (110°C) or more; Allow the engine to cool, add coolant to the overflow jug if it is low and check the level of coolant in the radiator, adding coolant until it is 3/4 in. (1.9 cm) below the filler neck and securing the radiator cap; Check the radiator shroud and ducting for blockage and remove any foreign matter; Inspect coolant hoses, engine block and water pump for visible leaks; Check the tension of the serpentine drive belt for the water pump; If no other problems are found, remove the load on the generator and restart the engine, check the coolant temperature and shut the engine down immediately if it starts to overheat, and consult the engine operator's manual
• Mast Lights Off, and Ballast Indicators on the Control Panel are Off.
  Cause: Loose lighting connections
  Fix: Check the connections inside the control box and inside each ballast box.
• Unit cranks, but will not start
  Cause: Fuel level low
  Fix: Check fuel level in tank.
• Overspeed or Underspeed Shutdown
  Cause: Engine speed not at 60.0 Hz with no loads on the generator
  Fix: Disconnect all loads and restart the generator and read the frequency (Hz) on the LCD display (with no loads the frequency should read 60.0 Hz); If the frequency is above or below 60.0 Hz, adjust the engine speed per the engine operator's manual for throttle adjustments on mechanically governed units and the electronic governor manual for electronically controlled units; MMG55FHDCAN6 units will need to contact John Deere with speed related issues since the engine is governed by the John Deere Electronic Engine Control Unit (ECU)
• WrnMaintenance — The period for servicing is set by the WrnMaintenance setpoint. The protection comes active if the running hours of the engine reach this value. 31
• Wrn RA15 fail — Warning alarm in case of lost connection to IGL=RA15 module. 30
• Wrn ECU Alarm — ECU alarm list is not empty. 29
• Vgen<, > — The generator voltage is out of limits given by Gen <V and Gen <V setpoints. 27
• Vgen unbal — The generator voltage is unbalanced more than the value of Volt unbal setpoint. 28
• Underspeed — During starting of the engine, when the RPM reaches the value of Starting RPM setpoint, the starter is switched off and the speed of the engine can drop under Start RPM again. Then the Underspeed protection becomes active. Protection evaluation starts 5 seconds after startup. 26
• Ubat — Battery voltage is out of limits given by Batt Undervolt setpoints. 25
• TimingSensor SPN:637

Compiled from service & troubleshooting documentation across every generator set that uses the Isuzu 4LE1NYGV-03.

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

• Air filter: Isuzu 5864014350 Isuzu 8972599390 Donaldson P775687 Donaldson P821575 Donaldson P822858 Wix 46368 Baldwin PA3850 Wix 46438NP
• Fuel filter: Isuzu 8944015310 Donaldson P502166 Wix 33263 Baldwin PF981
• Oil filter: Isuzu 5876100080 Donaldson P550162 Wix 51334 Ac Delco X45 Baldwin B179

Cross-referenced via Donaldson + OEM/engine-maker interchange — options to verify against your serial number, not confirmed for every exact variant.

• Hitachi EX40U — Excavator Compact
• Hitachi EX50U — Excavator Compact
• Hitachi EX55UR-3 — Excavator Compact
• Hitachi EX58MU — Excavator Compact

Other equipment known to use this engine, via filter-application cross-reference — useful for sourcing parts even when your exact machine isn't listed elsewhere on this page.