Polaris General Code 65590 And 65591

There’s nothing quite like the feeling of hitting the trail in your Polaris General. But there’s also nothing that kills the vibe faster than a sputtering engine, a sudden loss of power, and that dreaded check engine light flashing on your dash. You pull over, check the display, and see it: a diagnostic trouble code. You’re not alone if you’ve seen this happen.

We promise this guide will demystify the frustratingly common polaris general code 65590 and 65591. We’re going to break down exactly what these codes mean, what causes them, and give you a clear, step-by-step roadmap to diagnose and fix the problem yourself, saving you a trip to the dealer and getting you back to what you love.

In this article, we’ll cover the tools you’ll need, the most common culprits from spark plugs to fuel delivery, and the preventative maintenance that can stop these codes from ever appearing again. Let’s get your rig running right.

What Are Polaris General Code 65590 and 65591 Telling You?

Before we grab any tools, let’s understand what your machine is trying to communicate. These codes are specific signals from your Engine Control Unit (ECU) that it has detected an engine misfire. A misfire is simply a failure of a cylinder to combust its fuel-air mixture properly.

The ECU is smart. It monitors the rotation of the crankshaft, and when a cylinder misfires, it causes a tiny, momentary slowdown in that rotation. The crankshaft position sensor picks this up, and the ECU flags a code to tell you which cylinder is having the problem.

Code 65590: This points to an Engine Misfire Detected on Cylinder #1. On a Polaris General, this is the cylinder on the PTO (Power Take-Off) side of the engine, which is the rear cylinder, closest to the clutch.
Code 65591: This indicates an Engine Misfire Detected on Cylinder #2. This is the cylinder on the MAG (Magneto) side of the engine, which is the front cylinder, closest to the flywheel.

Seeing one of these codes isolates the issue to a specific cylinder’s components. If you see both codes pop up, it often suggests a more systemic problem affecting the entire engine, like bad fuel or a clogged air filter.

Common Causes: The Usual Suspects Behind a Misfire

A misfire can be traced back to one of three core areas: spark, fuel, or air/compression. The key to an efficient diagnosis is to start with the simplest and most common causes first. This is one of the most important polaris general code 65590 and 65591 tips we can offer—don’t start with the hardest fix!

Ignition System Woes (The “Spark” Problem)

The ignition system is the number one culprit for misfire codes. If the spark isn’t strong enough or doesn’t happen at the right time, you won’t get proper combustion.

Fouled or Worn Spark Plugs: This is the most common cause. Plugs get covered in carbon, oil, or fuel over time, weakening the spark. They are a cheap and easy first part to replace.
Damaged Spark Plug Wires or Boots: The wire carries the high voltage to the plug. Cracks, corrosion, or a loose-fitting boot can cause the spark to ground out before it reaches the plug.
Failing Ignition Coil: The coil transforms the machine’s low voltage into the high voltage needed for a spark. A weak or failing coil will produce a weak spark, leading to misfires, especially under load.

Fuel System Faults (The “Fuel” Problem)

If the spark is good, the next step is to ensure the cylinder is getting the right amount of clean fuel. This is one of the most common problems with polaris general code 65590 and 65591.

Clogged or Dirty Fuel Injectors: Ethanol in modern fuel can leave deposits that restrict fuel flow, leading to a lean condition and a misfire.
Low Fuel Pressure: A weak fuel pump or a faulty fuel pressure regulator can starve the engine of the fuel it needs to run properly.
Bad or Contaminated Fuel: Water in the fuel from condensation or a bad fill-up is a classic misfire cause. Old, stale gas that has lost its volatility can also fail to ignite properly.

Air & Mechanical Issues (The “Compression” Problem)

This category is less common but more serious. If spark and fuel are good, the engine itself may have an issue preventing proper combustion.

Severely Clogged Air Filter: An engine needs to breathe. If the air filter is packed with dirt, it can choke the engine, foul the plugs, and cause misfires.
Incorrect Valve Clearance: If the valves are too tight, they may not close completely, causing a loss of compression and a misfire. This is a maintenance item that is often overlooked.
Low Engine Compression: This is the worst-case scenario, pointing to internal engine wear like worn piston rings or a bad valve seat.

Your Step-by-Step Diagnostic Polaris General Code 65590 and 65591 Guide

Alright, time to get hands-on. Follow these steps methodically. The goal is to confirm the problem before you spend a dime on parts. This is how to polaris general code 65590 and 65591 troubleshooting is done right.

Essential Tools for the Job

Having the right tools makes the job easier and safer. You don’t need a full professional shop, but these will cover most of the diagnostic steps.

Basic socket and ratchet set
Spark plug socket (deep well, correct size for your General)
Torque wrench
Digital Multimeter (for testing electrical components)
Feeler gauges (for checking valve lash)
Flashlight or headlamp

Step 1: The Simple Checks (Start Here!)

Before you tear anything apart, check the basics. You’d be surprised how often the fix is simple.

Check Your Fuel: Is the tank nearly empty? Did you just fill up from a questionable gas station? If the fuel is more than a few months old, consider draining it and adding fresh, high-quality gasoline.
Inspect the Air Filter: Pop the cover off your airbox. Is the filter caked in dust and debris? If so, clean or replace it. This is a critical first step.
Visual Wire Inspection: Look closely at the spark plug wires. Do you see any obvious cracks, melted spots, or corrosion on the ends? Ensure the boots are seated firmly on the spark plugs and the ignition coil.

Step 2: Diving into the Ignition System

If the simple checks don’t reveal anything, it’s time to investigate the spark. Remember to work on a cool engine.

Pull and Inspect the Spark Plugs: Remove the spark plug from the cylinder that flagged the code (Cylinder #1 is the rear, #2 is the front). Look at the tip. Is it black and sooty (running rich)? White and blistered (running lean/hot)? Or wet with oil or fuel?
Replace the Plugs: Spark plugs are inexpensive. If they look anything but light tan or grey, it’s best to replace them. We highly recommend using the OEM-specified NGK MR7F plugs. Ensure you gap them correctly and use a torque wrench for installation.
Test the Plug Wires: Set your multimeter to measure resistance (Ohms Ω). Disconnect a plug wire from both the coil and the plug. Touch one probe to each end of the wire. A good wire should have a resistance of a few thousand ohms. An infinite reading (OL) means the wire is broken internally.
Test the Ignition Coil: You can test the coil’s primary and secondary resistance using your multimeter. You’ll need to consult your service manual for the exact specifications, but this test can quickly tell you if the coil has failed.

Step 3: When to Call for Backup

If you’ve replaced the plugs, and the wires and coil test good, the problem likely lies in the fuel system or with a mechanical issue like valve clearance. These tasks can be more complex.

Checking fuel pressure requires a special gauge, and checking valve clearance requires removing the valve cover and rotating the engine to top-dead-center. While doable for a skilled DIYer, this is the point where you should honestly assess your comfort level.

Pro Tip: If you’re not confident in performing these advanced checks, there is no shame in taking it to a trusted mechanic. It’s better to pay a pro than to cause more significant damage. The benefits of polaris general code 65590 and 65591 diagnosis are knowing when to stop and ask for help.

Best Practices for Preventing Misfire Codes

The best repair is the one you never have to make. Following a solid maintenance schedule is the core of our polaris general code 65590 and 65591 care guide. It’s not just about reliability; it’s also about performance and longevity.

A Proactive Maintenance Schedule

Change Spark Plugs Regularly: Don’t wait for a misfire. Change your plugs as recommended in your owner’s manual, or more frequently if you ride in harsh conditions.
Use Quality Fuel & Stabilizer: Always use fresh, high-octane fuel. If your General is going to sit for more than a month, add a quality fuel stabilizer to prevent the gas from breaking down.
Maintain Your Air Filter: Your air filter is your engine’s only defense against dirt. Check it before every ride and clean or replace it as needed.
Run a Fuel System Cleaner: Every few months, add a bottle of reputable fuel injector cleaner (like Sea Foam or Techron) to a full tank of gas to keep the injectors clean.

Sustainable and Eco-Friendly Care Tips

A well-maintained machine is a happy machine, and it’s also better for the environment. Following sustainable polaris general code 65590 and 65591 best practices is easier than you think.

An engine that isn’t misfiring burns fuel more completely and efficiently. This means you use less fuel and release fewer unburnt hydrocarbons into the atmosphere. A clean air filter and proper spark contribute directly to a cleaner-running, more eco-friendly polaris general code 65590 and 65591-free ride.

Frequently Asked Questions About Polaris General Code 65590 and 65591

Can I still drive my General with these codes?

It’s not recommended for long distances. A persistent misfire can allow unburnt fuel to enter the exhaust, potentially damaging the catalytic converter over time. It also means you’re down on power, which can be unsafe on the trail. Limp it back to the truck or camp, but don’t continue your ride.

Do I need a special tool to read these codes?

No! One of the great things about the Polaris General is that the diagnostic trouble codes (DTCs) can be read directly on the instrument cluster display. Simply follow the prompts when the check engine light comes on to view the active codes.

What’s the difference between the PTO and MAG side of the engine?

It’s just a way to identify the cylinders. The PTO (Power Take-Off) side is where the clutches are—this is the rear cylinder (#1). The MAG (Magneto) side is where the flywheel and stator are—this is the front cylinder (#2).

Why did both codes 65590 and 65591 appear at the same time?

When both cylinders misfire, look for a cause that affects the whole engine. The most common culprits are bad fuel, a severely clogged air filter, or low fuel pressure from a failing fuel pump.

Tackling a check engine light can feel intimidating, but codes 65590 and 65591 are very manageable for a DIYer. By following a logical diagnostic path—checking air, then spark, then fuel—you can pinpoint the issue without just throwing parts at it. Remember that regular maintenance is your best defense against being stranded on the trail.

Now you have the knowledge and the confidence to solve this common problem. Get those tools out, get your hands dirty, and get your General running like it should. Ride safe, and we’ll see you on the trail!

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Thomas Corle

Founder & Automobile expert at FatBoysOffroad

Automobile expert and off-road enthusiast, sharing in-depth knowledge of vehicles, gear, and adventures. Helping readers make smart decisions and enjoy the thrill of off-roading safely and confidently.