Kohler Generator "Locked Rotor" Fault?

There are few things more frustrating than a critical fault code on your Kohler or Rehlko generator, especially when you're far from shore. One of the more confusing errors owners encounter is the "Locked Rotor" fault—confusing, because in many cases, the engine still turns over freely.

If you're seeing this alarm but can confirm the engine isn't seized, there's a very common culprit, and it's a fix you can often handle yourself.

The Symptom: "Locked Rotor" Alarm, But the Engine Cranks

You press the start button. You hear the starter engage and the engine begin to crank, but it never fires up. Instead, your digital control panel displays the "Locked Rotor" fault. This error is designed to protect the generator, but when the engine is clearly turning, it points to a sensor failure rather than a mechanical one.

The Likely Cause: A Failed Crankshaft Position Sensor

In the vast majority of these cases, the issue lies with a failed Crankshaft Position Sensor (CPS), part number GM39600.

This small but vital sensor's job is to tell the generator's brain that the crankshaft is spinning. If the controller doesn't receive this signal, it assumes the engine is seized and shuts down the start sequence. When the sensor fails, it can't send the signal, leading to a false conclusion.

How to Confirm and Fix the Issue

1. Safety First: Always disconnect the battery power to your generator before beginning any diagnostic or repair work.
2. Locate the Sensor: The CPS is typically located on the engine block, positioned to read the movement of the flywheel. Consult your service manual for the exact location.
3. Inspect Wiring: Before replacing, check the wiring and connector for any obvious signs of damage, corrosion, or a loose connection.
4. Replacement: If the wiring looks good, the next step is to replace the sensor. It's typically held in place by one or two bolts.
5. Reconnect and Test: Reconnect battery power and attempt to start the generator. A new GM39600 sensor will almost always resolve the fault.

Commonly Affected Kohler/Rehlko Models:

We've Got the Part You Need

A failed sensor shouldn't ruin your trip. We stock the genuine GM39600 Crankshaft Position Sensor and can get it to you quickly.