Polaris UTV Engine Miss Fire Codes. 65590,65591,65592

Probably one of the most common Polaris trouble codes discussed on the internet is the dreaded miss fire codes. 65590,65591,65592 ECU Misfire Codes. After many years in the UTV business I get to see some common themes and problems that many people experience with their Polaris side x sides.

I am going to talk to you about the misfire codes specifically. My theory on why some Polaris’s will throw this code and nothing seems to solve it.

When people ask questions on internet forums about the misfire codes the overwhelming response is, the drive belt has gone bad and the engine speed does not match the wheel speed.

Polaris Engine Codes

Polaris UTV Engine Missfire Codes 65590, 65591, 65592

Here is what I see wrong with this response now days. This was the problem when owners of UTV’s the first couple of years when the UTV’s came on the market owners did not know about belts slipping and getting burnt and or destroyed causing clutch problems etc. 

With more than a decade of Polaris side x sides in the market, the belt is one of the first things that gets replaced because it has become common knowledge for this to cause the misfire code.

Here is what I see getting thrown at your Polaris to fix this problem, Belts, Spark plugs, spark plug wires and clutches.

After throwing hundreds and hundreds of dollars at the problem with no resolution they go back to the world wide web to find the real answer. Hoping that someone wrote down the magical fix!

Don’t get me wrong there are multiple possibilities that will cause the engine miss fire and engine codes. 

  • Burnt belt causing the clutches to jump in RPM
  • Low engine compression-This is a big one
  • Valves out of adjustment
  • Fuel – Contamination
  • Ignition – rare

Here is a Youtube vide I have made to diagnose Polaris misfire codes 65590,65591,65592.

The computer can detect a misfire in an engine way sooner than you and I could feel it physically.

This is what I would recommend checking over on your Polaris to try and figure out the misfire.

  • Check belt and clutches to make sure they are in good shape.
  • Engine compression-our 4500+ elevation here with an XP 1000. 175lbs is good engine compression.
  • Check your valve lash. This is fairly easy you can watch my YouTube video to show you how.
  • Spark plugs and wires. You do not have to replace these if they are in great shape.

I have left the last one off of the check list because here is where I believe a lot of the mystery engine misfire codes come from when someone says they have tried all other fixes with no resolve.

High Octane fuel vs Ethanol Free Fuel. 

This is a major controversy on the internet that I read all the time and just shake my head.

Lots and lots of people will tell others to use high grade regular fuel. They have never had a problem and you should use fuel with Ethanol also it is better for your engine. Sometimes this is just poor advice! Don’t always believe what is getting written on the internet. It might not be what is best for your needs and UTV.

Amsoil does a great job explaining their testing results from Ethanol effects and what it does to your fuel inside of your tank.

For more information on their exact results, you can click on here to read more.

Here is the problem with Ethanol-it loves water and likes to bring more water particles to it.

Amsoil proved that fuel with Ethanol sitting 3 weeks in a glass tube. Ethanol will separate from the fuel. It is called Phase Separation. 

Ethanol Phase Separation.

Blue fluid is Ethanol and Clear is fuel.

If you drive your UTV every week and keep the fuel sloshing around you will probably never have a problem and this does not refer to you. But if you’re like me and your RZR sits for a month or longer, This article pertains to you especially if your UTV sits all winter long.

The Ethanol is heavier than water and immediately goes to the bottom of the glass container of fuel.

Here is where the real problem comes in referring to how Ethanol loves water!

All of our UTV’s including Polaris, Can-Am, Honda, Kawasaki, the fuel tanks are all vented to the air somewhere and this is when the moisture is pulled into the fuel tank and attaches to the molecules of the Ethanol. 

Before long the water starts getting more and more. Just sitting on the bottom of your fuel tank after several years of this bad choice of fuel option you just might end up with enough water in the bottom of your fuel tank that once in a while a small little portion gets sucked up with the fuel pump and it causes a small misfire that you cannot feel.

I never read of anyone on the internet that drains all the fuel in the tank and then dries it out with a towel or some way to eliminate any kind of fuel contamination.

The fuel tanks on Polaris do not have a drain in the bottom of the tank so the only way to get all the fuel out would be to pump it out and pull the fuel pump assembly and towel dry the rest, or remove the fuel tank and drain it that way.

If you run a really high compression engine you should stick with high octane fuel for your comfort or you can always purchase a bottle of octane booster and add it to the fuel tank according to the directions on the bottle.

This is my opinion – Ethanol fuel does not belong in any power sports vehicles or equipment period!

I hope you have safe and fun travels and this article might help you understand the effects of ethanol and fuel.

Until we ride again

Gary Madsen