Kohler Generator Fault Codes List and Easy Troubleshooting

As a Kohler generator user, I agree that these generators have robust performance and advanced technology. But still, it is a machine, and machines have issues. It is essential to troubleshoot these issues, for that’s where the Kohler generator fault codes list comes into action.

These fault codes provide valuable information about the potential problem and help to identify and resolve the issue.

In this guide, we will figure out the Kohler generator’s fault codes and explain what they mean so you can quickly troubleshoot your generator like a pro.

(Fault Code: AF) Auxiliary Fault

The AF fault code on Kohler generators indicates that the airflow sensor is not working correctly. The airflow sensor controls the air inflow toward the engine and is located between the air filter and the engine.

This is a small cylindrical shape sensor, but if this doesn’t work correctly, the engine will not start.

Possible Reasons for CodeAF:

  1. Faulty air flow sensor.
  2. Loos or faulty electric connection with a flow sensor.
  3. Dirty air filter.
  4. Dirty carburetor.
  5. Engine-related problems.


  1. Carefully check all the electric cables leading to the airflow sensor. Make sure the connection is undamaged and clean.
  2. Check the airflow sensor for dirt and damage. Keep the sensor properly clean and tidy.
  3. Check the air filter for dirt and blockage. Clean it if required.
  4. Make sure that the carburetor is not dirty and undamaged.
  5. Finally, check the engine for any possible problems.

(Fault Code: CC) Crank Cycle

The crank cycle typically refers to the rotation or revolution of the crankshaft in the engine, or we can say that “it is a cycle which rotates to run the engine.” The fault code CC refers to the cranking in the engine; it indicates that the generator is trying to rotate the crankshaft in the machine but is not starting. The first attempt shows CC1, CC2 for the second, and so on.

Possible Reasons for Code CC:

  1. The Battery is out of charge, or the battery connection to the generator needs to be fixed/faulty.
  2. The Starter of the generator is defective.
  3. The starter solenoid is wrong and does not supply enough current to the Starter.
  4. This code is also shown for seized engines.


  1. Make sure that all the connections are clean and tight.
  2. Check the battery voltage available to the starter solenoid. It must be above 10 – 11V.
  3. Press the start button. If you hear the starter solenoid cranking sounds, it means that the solenoid is bad.
  4. While starting the generator, if you notice that the Starter is sticking in the starting, it means that it is iStartery and needs replacing. (Hit once or twice with a heavy tool may work for you).
  5. And the last option of the engine seized is a problem where you need help to do it. Try to call an expert who can fix it.

(Fault Code: HB) High Battery Voltage

The fault code HB refers to the high battery voltage. This code is shown when the battery voltage exceeds the level of 16VDC. This error code is only possible once you charge your Battery with any outside tool. 

Drop an extra charge from your Battery to solve this problem.

(Fault Code: HE) High Engine Temp 

The error code HE indicates that the Kohler generator is running too hot. Your engine is running continuously for a more extended period, the temperature is too high, or there is air blockage.

A possible solution for this issue is to let the engine off for some time and double-check your generator’s coolant system, air inhalation, and exhaust.

(Fault Code: LB) Low Battery Voltage

The fault code LB indicates that the Battery is low in charge or dead. In this case, you need to test the Battery and recharge it. If it is dead, you must replace the Battery with a new one.

You can easily find a new battery in a local store or at Amazon.

(Fault Code: LCL) Low Coolant Level

The fault code LCL indicates that the liquid coolant in your generator is low and needs to be filled. Sometimes, this also happens due to a faulty sensor. So, to address this, you need to clean the sensor attached to the coolant system and place it back. If it is still not working, replacing it with a new one will be better.

(Fault Code: LOC)Loss of Coolant

The fault code of LOC “Loss of Coolant” indicates that the cooling mechanism is not working in your Kohler generator.

Possible Reasons for Code LOC:

  1. The pressure switch needs to be fixed.
  2. The flow sensor is not working correctly.
  3. The water pump impeller is not working.
  4. Improper water flow for cooling.
  5. It clogged the fuel injector.


  1. Check the pressure switch connection and clean it.
  2. Check the flow sensor’s electric connection and itself for fault. You can clean and replace as per requirement.
  3. Remove the water pump and check its impeller. If it is clogged, clean it and replace it. In case of a damaged impeller, it is recommended to replace it.
  4. Some Kohler generators use water as a coolant; in that case, you must check the water supply and quality to address this issue.
  5. There is less possibility of clogged fuel injection in this case, but if none of the above works, you can check that also.

(Fault Code: LOP) Low Oil Pressure

The fault code LOP indicates the oil pressure in the engine has fallen below the recommended level. Sometimes, it can also occur when the oil pressure is above the recommended level.

Possible Reasons for Code LOP:

  1. Low oil level in the engine.
  2. Faulty oil pump.
  3. Oil leaking.
  4. It clogged the air filter.


  1. Inspect the oil level in your generator. Ensure that the oil level is at the recommended mark.
  2. Check the engine for leakage. Leakage can cause a low oil pressure error code.
  3. Inspect the oil filter because a dirty oil filter can also cause low oil pressure.
  4. Check the oil pump; a faulty oil pump can trigger the LOP error.
  5. If you recently changed the oil. Verify the oil viscosity as recommended by Kohler in the manual guide.
  6. Suppose you are unable to resolve the issue with the above solutions. You need to contact the professional from the manufacturer’s service center.

(Fault Code: OC) Over Crank

The error code OC means that your generator has been cranking for a long and cannot start the engine. If your Kohler generator cranks it for more than 15 seconds and does not start, you need to switch it off manually because prolonged cranking can cause heat to build up in the starter motor and even damage it.

Possible Reasons for Code OC:

  1. Spark Plug faulty
  2. Air filter dirty
  3. Carburator
  4. Fuel supply line


  1. Check if the spark plug is getting sparks. You need to inspect the connection if it doesn’t get a spark.
  2. You also need to check the spark plug. Remove it and clean it or replace it if required.
  3. Clean the air filter and exhaust of the generator and remove any blockage in airflow.
  4. Check the fuel flow in the carburetor. Clean the carburetor if required.
  5. Fuel connection is also an essential factor to check. The OC fault code can also be caused by improper fuel supply.

(Fault Code: OF)Over Frequency

The fault code OF typically refers to over-frequency. It means that the electricity produced by your generator is too high. Kohler generators often show this fault code when the frequency is over 60 Hz. 

To fix this issue, you must remove the generator load and check the air filter. For further problems, you may call an expert.

(Fault Code: OS) Over Speed

The fault code OS refers to the problem when the generator’s engine exceeds the specified safe limit range. The controller motor, the governor, and a bad control panel can cause this fault.

Check the controller motor and also have a close check on the controller arm.

(Fault Code: OU) Over Voltage

The OU fault code is typically triggered when the generator voltage is too high from the recommended level. For example, if a 20KVA generator produces an output of 20+KVA, the Kohler generator’s sensor will register this as an overvoltage fault.

Possible Reasons for Code OU:

  1. AVR malfunction
  2. Potentiometer problem
  3. Generator Overspeed
  4. Capacitive load
  5. Excitation cleaning break
  6. Gain setting out
  7. Control panel setting


  1. Check the AVR and all its connection cables.
  2. Check the Potentiometer; if it does not exceed the limit, it means that the Potentiometer is faulty.
  3. We need to check the generator speed; if the generator runs over speed, we should solve the over-speed fault first.
  4. Check if any capacitive load is connected to the generator—for example, the voltage controller.
  5. We need to check the Excitation cleaning breakage in AVR.
  6. Gain setting can also cause this fault when you run your generator on a load shading schedule or using auto mode in a low main electric line.
  7. In this case, you need to check the control panel setting for ratted voltage. We may have saved ratted volts lower than required.

(Fault Code: UF) Under Frequency

The fault code OF typically refers to over-frequency. It means that the electricity produced by your generator is too high. Kohler generators often show this fault code when the frequency is over 60 Hz. 

To fix this issue, you must remove the generator load and check the air filter. For further problems, you may call an expert.

You May Like To Read: How To Solve Generac Generators Fault Codes.

(Fault Code: UU) Under Voltage

The fault code UU is triggered when the generator voltage falls below the recommended level. For example, if a 20KVA generator drops its output to 10KVA, the Kohler generator’s sensor will register this as an under-voltage fault.

Possible Reasons for Code UU:

  1. AVR malfunction
  2. Potentiometer problem
  3. Rectifier problem
  4. The generator is under speed.
  5. Sudden torque load
  6. Excitor or main winding
  7. Varistor short


  1. Check the AVR and all connections and adjustments of the AVR.
  2. A potentiometer is used to control voltage in a specific limit. If the voltage level exceeds the Potentiometer limit, there is no problem. You must check the rectifier to see if the voltage is below or over the Potentiometer. Any diode in the rotating rectifier may be faulty. 
  3. We need to check the generator speed. If the generator is running under pace, it is essential to solve the under speed first, which I mentioned above.
  4. If the fault UU occurs during on-load running, you may check if any appliance requires extra time at sudden times. This is normal in these cases.
  5. If exciting or primary wanding is naked or short, this may also cause under voltage in Kohler generators.
  6. Varistor shortage is another cause for this fault code. In this case, the output from the rectifier will not reach the main router.

Kohler Generator Fault Codes List For Experts

This error code list is intended for experts and is not tailored for home users. It is important to note that the provided error code table is indicative, and for the most up-to-date information, refer to the technical data sheet specific to your engine’s software version. 

Should you require additional assistance or have any inquiries, please reach out to your nearest authorized Kohler service representative. 

For your convenience, abbreviations used in the list include SPN (Suspect Parameter Number) and FMI (Failure mode identification).

Jason Wallace
Jason Wallace

Jason Wallace is a skilled generator mechanic with over 10 years of experience. He shares his knowledge on WhatGenerators.com and is a resource for clients and colleagues. Jason has been recognized for his contributions to the industry and invited to speak at conferences and events.

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