AL20
SDMO High Engine Oil Temperature

Controller shows AL20 indicating oil temperature high; engine shuts down.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Insufficient engine oil, Blocked oil cooler on SDMO engine, Failed oil cooler thermostat, Heavy overload causing excessive engine heating

How to Fix / Troubleshooting

Safety first: Allow the engine to cool before touching any engine components. Do not bypass temperature protections.

  • Check oil level and quality: Verify oil level on the dipstick and top up if low. If oil is very dark or degraded, perform a full oil and filter change.
  • Inspect oil cooler: Clean external fins on the oil cooler (if air-cooled) or ensure coolant flow through the oil cooler (if water-cooled). Remove debris and scale.
  • Check oil temperature sensor: Test the sensor connected to the SDMO controller for correct resistance vs. temperature. Replace if readings are incorrect.
  • Review load conditions: Confirm that the generator is not being overloaded. Reduce load if necessary.
  • Reset AL20: After addressing the cause, clear the alarm and run the generator while monitoring oil temperature.
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Repair Difficulty

Medium 3/5

Required Part

Oil Temperature Sensor
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