21
UnclassifiedCooling
What This Code Means
Controller senses a short circuit in starter solenoid circuit; Governor Actuator Overload; Governor actuator duration of operation at or near full-duty cycle is beyond the design limit; Low Oil Pressure Cutoff Switch fault; Temperature Sending Unit fault
Possible Causes
- •Exhaust restriction
- •Loose or damaged connections at starter motor
- •Shorts and/or grounds at solenoid
- •Excessive load
- •Air intake restriction
- •Air leak in fuel system
- •Governor linkage binding
- •Incorrect high idle adjustment
- •Faulty injectors
- •Incorrect injection pump timing
- •Low compression
- •Faulty connections in wiring harness
- •Loss of switch continuity
Suggested Actions
- 1Check injectors
- 2Check connections at starter motor
- 3Check shorts and/or grounds at solenoid
- 4Check load
- 5Check air intake restriction
- 6Check exhaust restriction
- 7Check air leak in fuel system
- 8Perform fuel flow test
- 9Check governor linkage for binding
- 10Check high idle adjustment
- 11Check injection pump timing
- 12Check compression
- 13Check connections in wiring harness
- 14Check switch continuity
ASK RUDY ABOUT THIS FAULT
Get a diagnosis walkthrough for 21 on your specific Onan unit — cited to the OEM manual, not a forum guess.
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