Onan RV generator fault codes
RV generators shut down and store a fault code for conditions like low oil, overspeed, high temperature or failure to start.
How to read the code
Read the blink code on the status light or the numeric fault on the panel. Always check oil level first — low oil is the single most common shutdown.
All documented codes
Fault 2 (Low Oil) danger
Low oil pressure fault (a first-level fault shown as two blinks, code 2). The low-oil-pres… Fault 3 warning
First-level 'service check' fault. Three blinks tell you the controller has logged a probl… Fault 12 warning
Overvoltage fault. The controller could not keep the output voltage at the rated value (ou… Fault 13 warning
Undervoltage fault. The controller could not hold the generator's AC output at rated volta… Fault 14 warning
Overfrequency fault. The engine governor could not hold the rated output frequency and the… Fault 15 warning
Underfrequency fault. The engine governor could not keep the engine spinning fast enough t… Fault 19 warning
Governor actuator fault. The controller detected an open or shorted circuit in the electro… Fault 27 warning
Voltage sense fault. The controller was unable to sense the generator's output voltage, so… Fault 29 warning
High battery voltage fault. The voltage across the genset's starting battery system was ab… Fault 31 danger
Overspeed fault. The engine speed exceeded 3400 rpm, so the controller shut the generator … Fault 32 warning
Low cranking speed fault. During start the engine cranked slower than about 180 rpm for mo… Fault 36 warning
Engine Stopped fault. The engine stopped on its own without the controller commanding a sh… Fault 38 warning
Overcurrent (field overload) fault. The generator saw excessive current from low-power-fac…
Low oil pressure fault (a first-level fault shown as two blinks, code 2). The low-oil-pres… Fault 3 warning
First-level 'service check' fault. Three blinks tell you the controller has logged a probl… Fault 12 warning
Overvoltage fault. The controller could not keep the output voltage at the rated value (ou… Fault 13 warning
Undervoltage fault. The controller could not hold the generator's AC output at rated volta… Fault 14 warning
Overfrequency fault. The engine governor could not hold the rated output frequency and the… Fault 15 warning
Underfrequency fault. The engine governor could not keep the engine spinning fast enough t… Fault 19 warning
Governor actuator fault. The controller detected an open or shorted circuit in the electro… Fault 27 warning
Voltage sense fault. The controller was unable to sense the generator's output voltage, so… Fault 29 warning
High battery voltage fault. The voltage across the genset's starting battery system was ab… Fault 31 danger
Overspeed fault. The engine speed exceeded 3400 rpm, so the controller shut the generator … Fault 32 warning
Low cranking speed fault. During start the engine cranked slower than about 180 rpm for mo… Fault 36 warning
Engine Stopped fault. The engine stopped on its own without the controller commanding a sh… Fault 38 warning
Overcurrent (field overload) fault. The generator saw excessive current from low-power-fac…