Isuzu S4L2-W461ML Engine Engine

• Unit cranks, but will not start
  Cause: Fuel level low
  Fix: Check fuel level in tank. Verify fuel pump operation.
• Restricted air filter
  Fix: Inspect air filter for blockage. Refer to OEM engine operator’s manual for additional information.
• Overspeed or Underspeed Shutdown
  Cause: Frequency setting incorrect
  Fix: Disconnect all loads and restart unit. Read frequency (Hz) in the LCD window on controller. Frequency should read 60 Hz. If frequency is above 60 Hz, engine speed will need to be adjusted. Refer to the engine operator’s manual for throttle adjustment information.
• Oil pressure switch failure
  Fix: Refer to OEM engine operator’s manual to identify corrective action.
• Oil leaking from engine
  Cause: Visually inspect the engine for leaks.
• Mast Lights On But the Light Output is Low
  Cause: Fixture and/or lens is dirty. Lamp worn due to normal use. Damaged or loose electrical connections. Generator output incorrect. Low transformer output.
  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. Replace lamp. Check the mast coil cord, mast junction box and mast light connections. Check the incoming voltage to the ballast. Incoming voltage should be 120V +/-5V. If the voltage is incorrect, the engine speed may need to be adjusted or the generator may require service. The voltage from the transformer should read approximately 400VAC as the light 'strikes' (induces an arc), then drop and slowly rise back up to stabilize at 240-260VAC. On hard wired models, remove the mast junction box cover and insert the wire probes into the connector blocks for the light and ground. If proper voltage is not achieved, perform capacitor check to determine if the capacitor or coil needs to be replaced.
• Mast Lights Off, but Ballast Indicators on Control Panel are On.
  Cause: Light fixture is too hot. Faulty lamp connection. Lamp broken. Loose lighting connections. Damaged or loose electrical cord
  Fix: Allow light to cool 10-15 minutes before restarting. Check that the lamp is tight in the socket. Check for broken arc tube or outer lamp jacket, broken or loose components in lamp envelope, or blackening/deposits inside tube. Check the connections inside the mast junction box and each mast light housing/socket. Check the mast electrical cord for damage and check the cord connections inside the control box.
• Mast Lights Off, and Ballast Indicators on the Control Panel are Off.
  Cause: Loose lighting connections. Generator output incorrect. Low transformer output.
  Fix: Check the connections inside the control box and inside each ballast box. Check the incoming voltage to the ballast by checking the available voltage on the GFCI receptacle. Incoming voltage should be 120V +/- 5V. If voltage is incorrect, the engine speed may need to be adjusted or generator may require service. The voltage from the transformer should read approximately 400VAC as the light 'strikes' (induces an arc), then drop and slowly rise back up to stabilize at 240-260VAC. On hard wired models, remove the mast junction box cover and insert the wire probes into the connector blocks for the light and ground. If proper voltage is not achieved, perform capacitor check to determine if the capacitor or coil needs to be replaced.
• Low oil pressure shutdown (000139)
  Cause: Low oil level
  Fix: Verify oil level on dipstick. Add oil, if needed.
• Leakage in coolant hoses, engine block, or water pump
  Fix: Inspect for visible leaks. Verify tension of water pump serpentine drive belt.
• High coolant temperature shutdown
  Cause: Low coolant level
  Fix: Add coolant if needed. Allow engine to cool, then check coolant level in radiator. Restart engine and check coolant temperature. Stop engine immediately if coolant temperature is 210°F (99°C) or more.
• Blockage in radiator
  Fix: Inspect radiator shroud and ducting for blockage and remove any foreign matter.

Compiled from service & troubleshooting documentation across every generator set that uses the Isuzu S4L2-W461ML.

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.