How to Fix Fault Code 22 on Onan Generator? (Error Solved!)

onan generator code 22

There are situations when your Onan generator may grind to a halt and start blinking the fault code 22 on the control switch.

Fault code 22 can be caused by several different problems your generator may be having while working, but sometimes can be also just a simple misreading of the flashing pattern.

Whichever the case may be, it is very important to determine what is the cause for your generator to suddenly shut down on its own.

When you are away from the convenience of the power grid, your only source of electric energy is your generator, so it is very important that it functions properly.

Further on, I will explain what are the causes of fault code 22, and which of them you can fix yourself and for which you will need specialist assistance.

So, how to fix fault code 22 on the Onan generator? To solve the fault code 22 on Onan generator, just check and follow the steps below:

–           Step #1: Overloading the generator

–           Step #2: Check the state of the air filter

–           Step #3: Exhaust system

–           Step #4: Spark plugs

–           Step #5: Fuel lines and filter

Some solutions are very straightforward and fall under user maintenance, but some require specialized tools to diagnose and repair, and attempting them can void your warranty.

What is Fault Code 22 on Onan Generator

The generator in your RV is intended to be a reliable source of electricity, and if it malfunctions you will be able to power your appliances only as long as you have a charge left in your deep cycle battery.

In case that it is not working properly, your camping trip can quickly become an unpleasant and annoying experience.

Thus, keeping your generator in working condition should be your primary concern.

In most cases, fault code 22 is very easy to fix, though any malfunction that shuts down your generator may be an anxiety-inducing experience.

The fault code 22 means that the generator engine’s governor/actuator is running continuously at its maximum output for 10 seconds.

There are several ways how the governor/actuator of the engine can be overloaded, but first, let’s see how to establish whether you are really getting the fault code 22.

Read also:

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Reading the Fault Code on Onan Generator

Onan generators have a simple, yet elegant way of displaying fault codes, the control switch is equipped with a signal light that blinks in a certain pattern depending on the code.

Your generator will be blinking in a certain pattern for 5 minutes before stopping, but you can easily retrieve the fault code.

  • The first thing you will need to do is press the STOP/PRIME button three times in quick succession.
  • This will make the indicator start blinking in the pattern of three flashes with a pause between them, this is fault code three that means that there was some fault described by a two-digit code.
  • Next, you will have to press the STOP/PRIME button and hold it for around a second.
  • When you release the button, the control switch indicator will start flashing the two-digit code. It will first blink several times for the first digit, then after a short pause blink for the second digit of the code, after a long pause, it will repeat the pattern.
  • Flashing will stop on its own after 5 minutes, but you can interrupt it yourself by pressing the STOP/PRIME button twice.

If you see that control switch light blinks twice and then after a short pause twice more times, you have the fault code 22 situations.

If the blinking pattern is different, then it is a different fault code you have to deal with.

Troubleshooting Fault Code 22

The first thing you need to understand before trying to fix the fault code 22 issue is the governor’s function.

In the simplest terms, the generator’s engine is spinning at a constant speed so that it could produce the AC of constant frequency, but the current is regulated by the engine’s load.

When a load on the engine is increased, fuel supply to its cylinders needs to be increased also, and that is done by the governor automatically.

Some of the causes of the fault code 22 are very complex to diagnose, and should be left for professional technicians as trying to fix them could void the warranty.

But some are very easy to fix, and actually, it is recommended by both service and user manuals to be done by the user.

So here are things you can do if you are experiencing the fault code 22 on your Onan generator.

Check first for the simplest solutions

Step #1: overloading the generator

The most common cause of fault code 22 is overloading the generator with too many appliances.

So, the easiest thing to do when you are trying to fix this issue is to turn off appliances that have high current demands, such as electric stoves, ACs, battery chargers, etc.

One thing that can severely influence the power output of your generator is the altitude, because of the less oxygenated air, its engine can produce less power which in effect decreases the generator’s maximum power rating.

Step #2: Check the state of the air filter

The next most common problem is related to the fact the governor will try to respond to increased engine load by supplying more fuel to it, and load on the engine is measured by a drop of RPMs, which can be caused by dirty air filters.

So, you should also check the state of the air filter and replace it if it is needed, which should be apparent from the amount of dirt collected on it.

There is a chance that the fresh air duct, also known as air intake tube boot, is not clamped properly or even has slipped off

Step #3: Exhaust system

Drops in RPM of the engine can also be caused by the fouled exhaust, if it is obstructed there will be back pressure in the exhaust manifold which slows down pistons during the exhaust cycle, which in turn leads to slowing of the engine.

Thus, you need to check whether the exhaust is blocked and remove the blockage.

Step #4: Spark plugs

Spark plugs can be fouled by the soot of combustion, the ground electrode gap can be increased or completely eaten away.

All of these three things can ultimately lead to improper combustion and drop of engine RPM, which in turn can lead to the governor trying to increase the RPM by providing the maximum fuel.

“The consequence of this can be the fault code 22, so checking the spark plugs, their gap, cleaning, or replacing them if needed is a potential solution for the fault code 22.”

Another way that spark plugs can lead to the fault code 22 is if their cables are loose, so making sure that they are secure can fix the problem relatively easily.

The last possible cause for fault code 22, which you certainly will be unable to fix yourself unless you are experienced in rebuilding engines, is that generator’s engine could be just old and worn out and needs some serious servicing.

Step #5: Fuel lines and filter

The governor cannot measure the flow of fuel, but simply depending on the engine’s RPM allows for more or less fuel to be supplied to cylinders.

In case that the fuel flow is obstructed, very easily the governor can be overloaded which leads to the fault code 22.

Fuel flow is most often obstructed either by a kink in the fuel line, a leak on fittings or by a dirty fuel filter.

Checking and fixing either of these three potential problems is relatively simple, you can inspect the fuel line visually, but for replacing the fuel filter you will need a deep socket wrench.

Potential Issues That You Should Leave To Professionals

Besides these causes of fault 22, which you can fix by yourself, there are potential issues that you should leave to professional technicians, especially because by attempting to fix them you can void the warranty.

One of such potential issues is a faulty governor itself, though you can diagnose binding in it by turning the governor actuator rotor clockwise, other issues need specialized tools and professional servicing.

“If the fuel pump is faulty, you very likely will not have the tools needed to measure fuel pressure, so it is also needed to take your RV to a shop.”

Another problem that you will not be able to diagnose by yourself very easily is a leaky intake manifold, though replacing its gasket is relay simple this is a problem that is not very easy to diagnose.

Issues with PMG stator winding are also a bit tricky to diagnose, and very likely fiddling with it will void your warranty.

Prevent Fault Code 22 from Reoccurring

The fault code 22 arises, in essence, when the governor is unable to provide enough fuel for maintaining the proper RPM range of the engine.

So, preventing it from reoccurring boils down to making sure you perform the regular maintenance, allowing the engine to “breathe” freely.

You should make sure to replace the air filter at proper maintenance intervals, and also check its condition if you have used the generator in a very dusty environment.

Also, you should change the fuel filter when their service time also comes, in addition, to regularly check the health of the spark plugs.


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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