Onan Generator: “Fault 22”
warning RV generator fault codes
What it means
Governor actuator overload. The controller had to hold the governor actuator at full duty cycle — maximum pulse-width-modulated signal — for 60 consecutive seconds to keep engine speed up, and shut down. In other words the engine was being asked for more than it could deliver, for a full minute.
Most likely causes
- Too much load, particularly motor starting loads such as air conditioners most likely
- Engine down on power — restricted air filter, fuel restriction or a worn engine common
- High altitude or high ambient temperature reducing available output less common
Safe checks you can do yourself
- Turn off large loads, restart, and add them back one at a time to see which one triggers it.
- Avoid starting two air conditioners at the same moment — stagger them.
- Check the air filter and the fuel filter, since either can leave the engine short of power under load.
How to reset / clear Fault 22
- Reduce the load and restart.
- To re-display a logged code, press Stop three times within five seconds — the blinking times out after five minutes (fifteen on the HGJAA series). The controller keeps replaying the last fault even after the cause is gone; only a successful run clears it.
When to call a technician
It trips at loads the genset used to carry comfortably — that points at engine performance rather than at your appliances.
Accuracy notes
Do not confuse this with code 19. Code 19 is an electrical fault in the actuator or its harness and is a dealer job; code 22 is a working actuator being asked for too much, and is usually fixed by the person operating the generator.
Applies to
Onan Quiet Diesel HDKCA / HDKCB · Onan gensets with an electronic governor actuator
FAQ
What does Onan Generator code "Fault 22" mean?
Governor actuator overload. The controller had to hold the governor actuator at full duty cycle — maximum pulse-width-modulated signal — for 60 consecutive seconds to keep engine speed up, and shut down. In other words the engine was being asked for more than it could deliver, for a full minute.
How do I reset Onan Generator Fault 22?
Reduce the load and restart. To re-display a logged code, press Stop three times within five seconds — the blinking times out after five minutes (fifteen on the HGJAA series). The controller keeps replaying the last fault even after the cause is gone; only a successful run clears it.
What is the most common cause of Fault 22 on a Onan Generator?
The most likely cause is too much load, particularly motor starting loads such as air conditioners.
Related · Onan generator
Governor actuator fault. The controller detected an open or shorted… Fault 15
Underfrequency fault. The engine governor could not keep the engine… Fault 38
Overcurrent (field overload) fault. The generator saw excessive current…
Sources
- Operator Manual — RV Generator Set HDKCA / HDKCB (Spec A–E) — 0981-0173 (Issue 10), Section 4 Troubleshooting, Table 4-1 (Cummins Inc. (Onan Quiet Diesel))
● Checked against 1 manufacturer document · Last verified 2026-08-07 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual. How we verify