What are Onan generator fault codes?

How do I read Onan generator fault codes?

If you own an RV and it has a generator chances are it is an Onan generator. So that is the brand I will focus on in this post.

When you need your RV generator you expect it to be there for you. To start and run the way it is intended. But there are many variables that can cause the generator set to not start and perform as intended. For example, not exercising the generator on a regular basis. Unfortunately RV generators can sit in storage for months at a time causing fuel to gel up and the generator to not start, or if it does start to surge and not run properly. You can check out my video on YouTube about exercising your RV generators.

So, first and foremost preventive maintenance is your best friend when it comes to your RV generator. Your generator owner’s manual outlines some simple preventive maintenance to help ensure the generator will work properly when you need it. Simple steps like maintaining the proper engine oil level, and keeping battery connections clean and tight, but that is an entire other post.

Today we are talking about RV generator fault codes. Did you know your RV generator can communicate with you? IT can! When your Onan generator has a problem it can give you a fault code to help point you in the right direction to not only identify but correct the fault.

Onan generators use a diagnostic light that blinks in patterns to identify faults. If your generator is not operating properly, or shuts down, all you need to do is check the diagnostic light.

You can initiate the fault mode by pressing the generator control button three times within five seconds. There will be a short pause, then the status light will start flashing. 

The status light will flash a number of times, pause, then flash a number of times again depending on what the fault is. For example, let’s say it flashes three times, pauses and flashes two more times, the fault code 3-2 or 32. This particular code identifies a low cranking speed fault.

The fault codes start with one single flash and continue into the double digit codes. Your generator owner’s manual lists all the fault codes for your generator model. 

So what are some of the common fault codes?

If there is only one single flash it indicates a high engine temperature fault.

If there are only two flashes it indicates low oil pressure.

And if there are only three flashes it indicates a general service fault.

When you get a three flash general service fault you can isolate the fault further by pressing the Stop button one time to display a two-digit fault code. The two-digit code consists of 1, 2, 3, 4, or 5 blinks, a brief pause, and then 1 to 9 blinks.

For example, I mentioned earlier if you get three flashes a pause then two more flashes (code 32) it indicates a low cranking speed fault. If you go to your generator manual and look up code 32 it offers some corrective action steps you can take. For code 32 step 1 recommends you clean the positive and negative battery cable connections at the battery and at the generator set. Step 2 recommends recharging or replacing the battery after referring to the battery manufacturer recommendations, and Step 3 recommends replacing the generator engine oil based on proper viscosity based on ambient temperature. High oil viscosity can slow down the cranking speed. 

If you think you corrected a problem you can press the control button twice to reset and clear a code and see if it returns.

So, hopefully in some cases of generator faults you experience you can take corrective action and get the generator back in service.

For more serious faults Onan states high temperature and low oil pressure codes are the most critical. High temperature usually points to cooling system problems, while low oil pressure could mean low oil or internal engine damage.

Keep in mind that fault codes are a just starting point. More serious fault codes recommend you contact or visit an authorized Onan service center. If you experience recurring or serious codes, it’s time to call a professional.

There is more information about generator fault codes in your Onan generator manual, and if you want to learn more about preventive maintenance and other RV topics visit our RV Online Training site.

Happy Camping,
Mark Polk
RV Education 101
http://rveducation101.com/

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