Kohler generator code High Engine Temperature
High severity — The engine's coolant temperature sensor or high-temperature switch reported an overheat condition, sometimes shown on the controller as the abbreviated 'HE' fault, triggering a protective shutdown.
Applies to: Kohler liquid-cooled residential and commercial standby generators (RCA/RCL series) with an RDC2 controller
What it means
If the display is showing a clipped "HE" instead of spelling the fault out in full, that's just Kohler's shorthand for High Engine Temperature on some RDC2 screens — same fault, fewer characters. This one only shows up on the liquid-cooled RCA and RCL series, which tracks, since it's a coolant temperature sensor and a separate high-temperature switch doing the reporting; Kohler's air-cooled units don't have this exact fault because they don't have a liquid cooling system to monitor in the first place. Once either device reports the engine running hotter than its safe operating window, the RDC2 controller shuts the engine down on the spot rather than letting it keep running while temperatures climb further, since the whole point of the fault is to catch overheating before it becomes engine damage.
Most common causes
The usual reasons a liquid-cooled Kohler runs hot enough to trip this fault:
- Low coolant level or a coolant leak
- Radiator airflow blocked by debris or poor clearance
- Failing cooling fan or fan belt
- Faulty coolant temperature sensor
- Thermostat stuck closed
What you can check yourself
What's reasonable to check without opening the cooling system:
- Let the unit cool fully, then check coolant level in the reservoir/radiator (never open a hot cooling system)
- Clear leaves, grass clippings, or other debris from the radiator fins and enclosure vents
- Look for visible coolant leaks at hoses and the radiator
Because the fault can come from either the sensor or the switch rather than a genuine overheat, a unit that trips this repeatedly with coolant full and airflow clear is just as likely to have a bad sensor as an actual overheating engine — worth confirming before assuming the worst.
All codes for this brand
Every Kohler generator fault code — full list with what differs between models.
Related codes: Low Coolant Level and Engine Oil Pressure Low — both are protective shutdowns on the liquid-cooled line. See the Generator Runs Then Shuts Down symptom page for related troubleshooting.