Polaris General Code 65591 - Your Complete Misfire Troubleshooting

There’s nothing quite like that feeling. You’re deep on a trail, miles from the truck, and suddenly the check engine light flashes on your Polaris General’s dash. The engine sputters, loses power, and your heart sinks. You’ve just been hit with the dreaded polaris general code 65591.

We’ve all been there. That code is one of the most common issues General owners face, but it often sends people into a panic, thinking a catastrophic failure is imminent. We promise you this: that code is rarely a death sentence for your ride. In fact, it’s usually pointing to a simple, fixable problem you can likely handle yourself with basic tools.

In this ultimate guide from FatBoysOffroad, we’re going to break down exactly what this code means, walk you through a step-by-step diagnostic process from easiest to hardest, and give you the confidence to get your machine running right. Let’s get those wrenches turning and get you back on the trail.

What Exactly is Polaris General Code 65591? The Misfire Warning Explained

First things first, let’s demystify this code. When your dash flashes SPN 65591, it’s your General’s Engine Control Module (ECM) telling you one thing: “I’ve detected an engine misfire.”

A misfire happens when the fuel-air mixture in a cylinder fails to ignite at the right time. This can feel like a stutter, a hesitation, or a significant loss of power. The code itself is a general alert; it’s the starting point of your investigation, not the final answer.

You’ll often see a second number along with the code, called the FMI (Failure Mode Identifier). The most common ones for this issue are:

FMI 7: “Misfire Detected – Not Responding Properly.” This is the most frequent version. It means the ECM knows a misfire is happening consistently but can’t pinpoint the exact cause or cylinder from its sensor data alone.
FMI 2: “Misfire Detected – Data Erratic, Intermittent, or Incorrect.” This suggests the misfire is happening sporadically, which can sometimes make it trickier to track down.

Think of this code as a smoke signal. It tells you there’s a fire, but it’s your job to find out what’s burning. Luckily, the list of potential culprits is short and usually starts with the simplest components.

Common Culprits: The Top 7 Reasons You’re Seeing This Code

Before you start tearing your rig apart, it helps to know where to look. Over years of wrenching on these machines, we’ve found that the common problems with polaris general code 65591 almost always fall into a few key areas. Here’s your checklist, starting with the most likely suspect.

Worn or Fouled Spark Plugs: This is, without a doubt, the number one cause. A plug with a bad gap, carbon buildup, or oil fouling can’t create a strong enough spark to ignite the fuel.
Bad Spark Plug Wires or Caps: The electricity has to get to the plug. A cracked wire, a loose-fitting cap, or corrosion on the contacts can cause a weak or non-existent spark.
Failing Ignition Coil: The coil is responsible for transforming your battery’s 12 volts into the thousands of volts needed for a spark. If it’s weak, your spark will be too.
Fuel System Issues: Old, water-contaminated fuel or a partially clogged fuel injector can prevent the proper amount of fuel from reaching the cylinder, leading to a misfire.
Air Intake or Vacuum Leaks: A cracked intake boot between the throttle body and the engine allows unmetered air to enter, leaning out the fuel mixture and causing misfires.
Low Battery Voltage: The entire ignition system relies on solid voltage. A weak battery can lead to a weak spark, which the ECM interprets as a misfire. Never overlook the battery!
Drive Belt Problems: This one surprises people. A badly worn or slipping drive belt can cause erratic loads on the engine, which can sometimes fool the crankshaft position sensor and trigger a misfire code.

Tools of the Trade: Gearing Up for Your Diagnosis

You don’t need a full professional shop to tackle this job. A few key tools will make this diagnostic process smooth and effective. Having the right gear on hand prevents frustration and ensures you can test components properly.

Here’s what we recommend having in your toolbox:

Basic Hand Tools: A good socket set with extensions (including a dedicated spark plug socket), a set of screwdrivers, and pliers.
Multimeter: This is essential for testing voltage, resistance in your plug wires, and checking continuity. A basic digital multimeter is inexpensive and invaluable.
In-Line Spark Tester: This is the best tool for this job. It plugs in between your spark plug and the wire and has a small window that lights up, giving you a clear visual confirmation of a strong spark.
Feeler Gauge or Gapping Tool: For checking and setting the correct spark plug gap.
Essential Supplies: A can of contact cleaner, a tube of dielectric grease, and most importantly, a set of new, correctly gapped spark plugs (we recommend NGK plugs for the General).
Safety Gear: Always wear gloves and safety glasses.

Your Step-by-Step Polaris General Code 65591 Guide to Diagnosis & Repair

Alright, let’s get our hands dirty. Follow this polaris general code 65591 guide systematically. Don’t skip steps! The goal is to rule things out logically, starting with the easiest and most common fixes.

Step 1: Start with the Basics – Check the Obvious

Before you grab a single tool, use your eyes and ears. Pop the engine cover and take a look around. Are there any obviously disconnected wires? Is a vacuum hose dangling free? Is the spark plug cap seated firmly on the plug?

Next, check your battery terminals. Are they clean and tight? Use your multimeter to check the voltage with the machine off. A healthy battery should read at least 12.5 volts. If it’s lower, charge it fully before proceeding. A weak battery can cause all sorts of electrical gremlins.

Step 2: The Ignition System Deep Dive (The Most Likely Cause)

This is where you’ll find the problem 90% of the time. The ignition system is the heart of the combustion process.

First, pull the spark plug caps off. Inspect the inside for any white, powdery corrosion. Clean them out with contact cleaner if needed. Now, remove the spark plugs. Look at the tips. Are they black and sooty (running rich), white and blistered (running hot/lean), or coated in oil? Any of these conditions can cause a misfire. Even if they look okay, always check the gap with your feeler gauge. The spec for the General is typically 0.028 inches, but confirm with your service manual.

For the definitive test, use your in-line spark tester. Attach it to the spark plug, connect the plug wire, ground the plug’s threads against the engine block, and crank the engine. You should see a consistent, bright blueish-white spark. If the spark is weak, orange, or intermittent, you’ve found your problem area.

If the spark is weak on both cylinders, the ignition coil is a likely suspect. If it’s weak on only one, you may have a bad plug wire. You can test the resistance of the plug wires with your multimeter; consult your manual for the correct Ohm specification.

Step 3: Investigating the Fuel System

If you’ve confirmed you have a strong, consistent spark on both cylinders, it’s time to look at fuel. The first question is simple: how old is your gas? Fuel, especially ethanol-blended fuel, can go bad and absorb water over time, leading to poor combustion.

If the fuel is good, the next suspect is the fuel injectors. A simple trick is to place the tip of a long screwdriver on the body of an injector while the engine is running and press your ear to the handle. You should hear a distinct, rapid clicking sound. If one injector is silent, it might be stuck or electrically dead.

Checking fuel pressure is a more advanced step, but if you suspect a weak fuel pump, it might be necessary. This often requires a special gauge and is a point where some DIYers might choose to consult a professional.

Step 4: Hunting for Air Leaks

The engine needs a precise ratio of air to fuel. An air leak downstream of the sensors introduces extra, unmetered air, creating a lean condition that causes misfires.

Carefully inspect the rubber intake boots that connect the throttle body to the engine cylinders. These are notorious for developing small cracks, especially around the clamps. Bend and flex them while looking closely for any splits. Ensure the clamps are tight.

A common mechanic’s trick is to cautiously spray a small amount of carb cleaner or starting fluid around the intake boots while the engine is idling. If the engine RPM changes, you’ve found your leak. Warning: Be extremely careful doing this, as these fluids are highly flammable.

Step 5: When to Check Valves and Belts

If you’ve exhausted all the previous steps and the misfire persists, it’s time to look at mechanical causes. Incorrect valve lash (the clearance in your valvetrain) can affect cylinder compression and lead to misfires, but this typically requires a valve adjustment, which is a more involved job.

Finally, inspect your drive belt. A severely worn or glazed belt can cause jerky engagement and loading on the engine, which can, in rare cases, be misinterpreted by the ECM as a misfire. If your belt is old and worn, replacing it is good preventative maintenance anyway.

Best Practices for Preventing Misfire Codes in Your General

The best fix is the one you never have to make. Following a good maintenance schedule is the core of our polaris general code 65591 best practices. It’s about being proactive, not reactive.

Change Spark Plugs Regularly: Don’t wait for a code. Make spark plugs part of your annual tune-up. It’s cheap insurance.
Use Quality Fuel: Use fresh, high-quality gasoline and consider a fuel stabilizer if your machine sits for extended periods.
Battery Health is Key: Keep your battery on a tender during the off-season and ensure the terminals are always clean and tight.
Apply Dielectric Grease: When you change your plugs, put a small dab of dielectric grease inside the spark plug caps. This seals out moisture and prevents corrosion.
Perform Regular Inspections: Every time you wash your General, take five minutes to look over the intake boots, wires, and hoses. Catching a small crack early saves a headache on the trail.

A Note on Sustainable and Eco-Friendly Fixes

While fixing a mechanical code might not seem “green,” there are benefits. A properly running engine is an efficient engine. Following this sustainable polaris general code 65591 approach means your machine will burn fuel more completely.

This results in better fuel economy, saving you money and reducing your overall consumption. More importantly, it drastically reduces harmful emissions, ensuring the trails we love stay cleaner. An engine that isn’t misfiring and dumping unburnt fuel into the exhaust is a more eco-friendly polaris general code 65591 solution for everyone.

Furthermore, by diagnosing the problem correctly instead of just throwing parts at it, you reduce waste. When you do replace parts, be sure to dispose of old plugs, fluids, and batteries responsibly at your local auto parts store or recycling center.

Frequently Asked Questions About Polaris General Code 65591

Can I still drive my General with code 65591 active?

You can usually limp it back to the truck or shop, but we don’t recommend riding it for fun. A constant misfire sends unburnt fuel into the hot exhaust system, which can overheat and damage your catalytic converter—a very expensive repair. It’s best to diagnose and fix it as soon as possible.

How do I clear the check engine light after I fix the problem?

The easiest way is to disconnect the negative battery terminal for about 15-20 minutes. This will reset the ECM. Alternatively, the code will typically clear itself after the machine completes a few successful warm-up and cool-down cycles without detecting another misfire.

What is the absolute most common fix for this misfire code?

In our shop, it’s spark plugs, hands down. We estimate that 7 out of 10 machines that come in with this code leave with a new set of properly gapped NGK spark plugs and nothing more. Always start there.

My General is almost brand new. Why am I getting this code already?

It can happen. Sometimes a plug gets fouled during the engine break-in period from factory assembly oils. It could also be a simple loose connection from the factory, or in rare cases, a faulty part from the start. The diagnostic process is the same, regardless of age.

Tackling a check engine light like the polaris general code 65591 can seem intimidating, but it’s completely manageable. By following a logical, step-by-step process, you can isolate the issue, perform the repair, and save yourself a costly trip to the dealer.

Remember to start with the simplest, most likely causes—spark and fuel. Armed with a few basic tools and this guide, you have everything you need to solve the problem. Now, get out there, get it fixed, and get back to what matters most.

Stay dirty, 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.