How to Fix Fault Code 36 on Onan Generator? (Error Solved!)

onan generator code 36

The fault code 36 on the Onan generator is one of those issues that can have several causes, from something as banal as low fuel to some serious mechanical issues with the generator’s engine.

Of these several possible issues, some can be very easily diagnosed, while some are very tricky, while the fact that there are several possible causes necessitates some elbow grease to narrow down which one it is before fixing it.

When you are out in the wild, dry camping, it is very important to have a reliable source of electrical energy in your RV for powering all your appliances.

Otherwise, your trip can easily turn sour if you are wandering away from the convenience of the shore power.

So, how to fix fault code 36 on Onan generator? To solve the error code 36 on Onan generator, just check and follow the steps below:

–           Step #1 Check the fuel pump and filter

–           Step #2 Check carburetor or throttle body

–           Step #3 Check spark plugs

–           Step #4 Check altitude settings

What is Fault Code 36 on Onan Generator

The generator is the primary source of electricity for your RV in the absence of shore power, so it is very important that it works reliably.

Any time that generator just falls silent can be a reason for alarm, but fault code 36 can be sometimes comically easy to fix.

When the fault code 36 arises, it means that the generator’s engine has shut down without a shutdown command from the control board.

There are several reasons how this can happen, and I will be covering most of them later on in this article.

For the moment, let’s focus on how to properly ascertain that it is the error code 36 situation

Reading the Fault Code on Onan Generator

Before you try to troubleshoot some issue, you need to be aware of that issue presenting itself.

Chances are that you are fairly certain that you have the fault code 36 on your hands, but it doesn’t hurt to always make sure of it.

Onan generators have a very elegant way of displaying fault codes, and they will continue to do so for five minutes, but once that time has elapsed it will stop.

But despite this, it is fairly easy to retrieve the code again.

  • First, you need to locate the STOP/PRIME button on your generator, depending on the model it is either in the upper-left corner or the lower-right one.
  • You will need to press it three times inside the 5 seconds.
  • If you have done it properly, its indicator light will start flashing three times in succession followed by a pause, and then start to repeat the three flash pattern. This is fault code 3, which means that the generator has shut down due to some two-digit fault
  • Next, you will need to press the STOP/PRIME button once more and hold it for about a second.
  • The indicator light will start flashing a new pattern for the two-digit fault code. It will flash in two groups of blink separated by a pause, after the second group will come a long pause and the pattern then will repeat. The first group of flashes will be for the first digit, and the second group of flashes will be for the second digit of the fault code.

If you see that the indicator light flashes three times, pauses, and then six more, it means that you have the error code 36 on your hands.

The pattern will repeat itself and continue doing so for five minutes or until you shut it down by pressing the STOP/PRIME button twice in quick succession.

This fault code is easy to mix up with fault code 35 and 37, so you should count the second group at least twice before pressing the STOP/PRIME button again.

Be aware that fault codes 46 and 63 are not assigned, so if you by error mix up the first and the second digit, or miscount the first digit, it is still probably the fault code 36.

In case that you are seeing some altogether different patterns of flashes, you are dealing with a different fault code, and you will probably be able to find information on how to deal with it on our blog.

Read also:

>> How to Fix Fault Code 12 on Onan Generator?

>> How to Fix Fault Code 14 on Onan Generator?

>> How to Fix Fault Code 13 on Onan Generator?

>> How to Fix Fault Code 15 on Onan Generator?

Troubleshooting Onan LP generator fault code 36

The purpose of fault code 36 is to inform you that the generator has stopped without a shutdown signal from the control board, but it doesn’t really tell you what it did so.

There are several reasons that can lead to the generator’s engine shutting down without a command from the control board, and to fix any of these you first need to pinpoint the exact one.

So let’s get on with the process of figuring out the exact cause.

Check first for the simplest solutions

The most common cause, and also the easiest one to detect and fix is the low fuel or high environmental temperature.

If the engine runs out of fuel, it will grind to a halt without a signal from the control board, which is the reason for displaying fault code 36.

So, checking the fuel level is the very first thing to do, and you should be aware that the generator will not run if your tank is below ¼ full.

Also, in the case of gasoline models, if operated in a very hot environment it can experience the vapor lock, which prevents normal fuel supply.

For a vapor lock, it is enough to keep RV in the sun the whole day and the temperature in the generator’s bay can rise above 120 degrees Fahrenheit which can cause it.

When it comes to LPG models, it’s the cold weather that can cause problems with fuel vaporization.

In case that the problem is not with a low fuel level, you should start troubleshooting it.

Step #1: Check the fuel pump and filter

Because the most often fault code 36 happens because the generator has run out of fuel, you should first check the parts that influence the fuel supply.

The first indication that it is a fuel pump, is if your generator runs for 15-20 minutes and then shuts down with the fault code 36.

But before you start checking the pump, there is one potential cause of the fault code 36 in case that you have worked recently around the generator, pinched fuel line.

While it is literally impossible for a fuel line to become pinched on its own, there are chances that if you maybe have working on something and pinched it.

“One way to test whether your pump is properly working is to disconnect the fuel line from the carburetor and hold it above some container and crank the generator’s engine.”

This test will not exclude the fuel filter blockage but will narrow it down on one of those two in case that no fuel is flowing in the container or you have just a trickle from the fuel line.

Another way to make certain is to measure the voltage using the multimeter on fuel pump connectors while cranking the engine of the generator.

It should read just under 12V, and should not fluctuate, but if it fluctuates there is a problem with the pump and it needs to be replaced.

If the voltage is 12V but gas is just trickling or not flowing at all, then the problem is a dirty fuel filter.

Step #2: Check carburetor or throttle body

Depending on whether the engine of your generator is carbureted or with the injection system, you will need to check either the carburetor or throttle body.

You need to verify that all linkages, butterflies, and choke; are able to move smoothly, if there is some binding it needs to be cleaned or replaced.

Keep in mind that the carburetor on Onan generators is not designed to be fully cleaned and most likely will need to be replaced.

Step #3: Check spark plugs

In case that everything is OK with both fuel and carburetor/throttle body, the next likely issue is spark plugs suddenly not producing a spark.

Spark plugs can suddenly fail if they were neglected, but more often the issue is that spark plug cables became loose.

Just reconnecting it should clear the issue.

Step #4: Check altitude settings

In some odd cases, it is possible for the wrong altitude settings to bring the generator to halt, especially if you are driving on the road and climbing hills when it has stopped.

You can fix this simply by turning the settings knob to a more appropriate setting.

Causes of the Fault Code 36 You Can’t Fix

While the above problems you can fix yourself, there are some situations when you absolutely will need help from a repair shop.

In theory, there are some mechanical failures of the engine which could trip the fault code 36.

For example, if the engine has completely lost the oil pressure but the oil pressure sensor has failed to detect it, or the engine temperature probe has failed along with the water pump for some reason, which led to catastrophic overheating, and so on.

These mechanical issues happen very rarely and are beyond the scope of this article as you will not be able to easily diagnose them.

Besides these, there are some slim chances of faulty magnetos and improper gaps on them, which are also tricky to diagnose and fix.

Prevent Fault Code 36 from Reoccurring

Whether you decide to try to fix the causes of the fault code 36 yourself or opt for taking your RV to a repair shop, there are few things you can do to prevent it from reoccurring.

The first is to replace spark plugs and fuel filter when it is time to do it as a part of regular maintenance, in other words, every 500 working hours.

In case that you don’t use a generator very often, you should still change the fuel filter every three years.

In case that you very rarely use the generator, you should exercise it at least once in a couple of months.

This means to have it running for about an hour under about half of the load, which you can do by turning on at least one of the ACs your RV has.

This is especially important in the case that the generator’s engine is carbureted and will prevent accumulation of the varnish which can lead to binding of its various parts.

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Mike Gilmour

Hi, I'm Mike, co-founder, and editor of RV and Playa. My passion is traveling (with my RV) and enjoying the day at the beach (Playa)! Well, I originally created this blog as a way to share what I've learned by experimenting with the RV lifestyle, and I want to help others develop in life through new skills and opportunities.

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