There’s nothing that grinds a perfect trail day to a halt faster than that dreaded check engine light. You’re geared up, miles from the truck, and your 2017 Polaris RZR’s dash suddenly flashes codes 65590 and 65591. Your heart sinks a little. What now?
I get it. We’ve all been there. That cryptic string of numbers can feel intimidating, suggesting a complex and expensive problem. But I promise you, it doesn’t have to be.
In this complete guide from FatBoysOffroad, we’re going to pull back the curtain on these specific misfire codes. We’ll walk you through exactly what they mean, the most common culprits, and a step-by-step diagnostic process you can follow right in your garage or on the trail. Let’s get that machine running right and get you back to kicking up dust.
What Do Codes 65590 and 65591 Actually Mean?
First things first, let’s translate what your RZR is trying to tell you. These aren’t random numbers; they’re specific fault codes pointing to an engine misfire. A misfire happens when the fuel and air mixture in a cylinder fails to ignite properly.
Think of it like one of your engine’s cylinders not pulling its weight. This can cause rough idling, loss of power, poor fuel economy, and, if left unchecked, potential engine damage.
- Code 65590: Engine Misfire Detected – Cylinder 1 (This is the “Mag” or magneto-side cylinder, the one closest to the front of the vehicle).
- Code 65591: Engine Misfire Detected – Cylinder 2 (This is the “PTO” or power-take-off-side cylinder, the one closest to the rear).
Seeing one or both of these codes means the Engine Control Unit (ECU) has detected that a cylinder isn’t firing correctly. Our job is to play detective and figure out why. The fix is often simpler and cheaper than you think, but ignoring it is a surefire way to turn a small issue into a catastrophic one.
The Most Common Problems with 2017 Polaris RZR Showing Codes 65590 and 65591
Before you start tearing the whole engine apart, let’s focus on the usual suspects. In our experience, over 90% of misfire issues stem from one of three areas: spark, fuel, or air. This is one of the most important 2017 polaris rzr showing codes 65590 and 65591 tips we can offer: always start with the simplest and most common causes first.
Fouled or Worn Spark Plugs
This is, by far, the number one cause. Spark plugs are a wear item. Over time, the electrode wears down, or they can become fouled with carbon or oil, leading to a weak or inconsistent spark.
Bad Spark Plug Wires or Boots
The spark has to travel from the ignition coil to the plug. If the wire is cracked, corroded, or the boot isn’t sealing properly against the plug, that spark can arc to the engine block instead of igniting the fuel mixture.
Clogged Fuel Injectors or Fuel System Issues
If the cylinder isn’t getting the right amount of fuel, it can’t fire properly. A clogged or dirty fuel injector is a common culprit, especially if you’ve gotten a bad batch of gas or the machine has been sitting for a while.
Low or Inconsistent Fuel Pressure
The entire fuel system relies on steady pressure from the fuel pump. A failing pump or a clogged fuel filter can starve the engine of fuel, leading to misfires, especially under load.
Vacuum Leaks
Your engine needs a precise mixture of air and fuel. If there’s a crack in an intake boot or a loose clamp, unmetered air can get sucked in, throwing off the mixture and causing a lean condition that leads to misfires.
Your Diagnostic Toolkit: Gathering the Essentials
You don’t need a full professional shop to tackle this job, but having the right tools makes all the difference. A good 2017 polaris rzr showing codes 65590 and 65591 guide always starts with proper preparation.
- Basic Hand Tools: A good socket set (metric), a dedicated spark plug socket, and a set of wrenches.
- Spark Plug Tester: An inline spark tester is a cheap and invaluable tool that shows you if you’re actually getting spark at the plug.
- Multimeter: Essential for testing resistance in spark plug wires and checking other electrical components.
- Compression Tester: For more advanced diagnostics if the simple fixes don’t work.
- Torque Wrench: Crucial for properly tightening spark plugs without damaging the engine head.
- Safety Gear: Always wear safety glasses and gloves.
How to Fix 2017 Polaris RZR Showing Codes 65590 and 65591: A Step-by-Step Guide
Alright, let’s get our hands dirty. Follow these steps methodically. Don’t skip ahead. The goal is to diagnose, not just replace parts randomly. This is the core of how to 2017 polaris rzr showing codes 65590 and 65591 diagnostics should be done.
Step 1: The Simple Visual Inspection
Before you pick up a single tool, just look. Remove any necessary plastics to get a clear view of the engine. Check the spark plug wires. Are they seated firmly on the plugs and the coils? Do you see any cracks, burn marks, or corrosion? Follow the fuel lines and vacuum hoses. Look for anything that’s disconnected, cracked, or kinked.
Step 2: Digging into the Spark System
This is where we’ll solve most misfire problems. First, pull the spark plug wire off the affected cylinder (or both). Attach your inline spark tester between the plug and the wire. Have a friend crank the engine and look for a strong, consistent blue spark. No spark or a weak, orange spark indicates a problem with the coil, wire, or plug.
Next, pull the spark plugs. What do they look like? A healthy plug is light tan. A black, sooty plug means it’s running rich. A wet, oily plug could indicate a bigger mechanical issue. Regardless, if they look old, just replace them. They are cheap insurance. Make sure you use the correct plug (like the NGK MR7F) and gap it properly before installing.
Step 3: The “Swaptronics” Test for Wires and Injectors
If you have a misfire on just one cylinder (say, code 65590 on Cylinder 1) and new plugs didn’t fix it, it’s time for a pro diagnostic trick. Swap the spark plug wires between Cylinder 1 and Cylinder 2. Clear the codes and run the engine. Did the code move to Cylinder 2 (now showing 65591)? If so, you have a bad plug wire!
You can do the same thing with the fuel injectors. Swap the injector from Cylinder 1 to Cylinder 2. If the misfire code follows the injector, you’ve found your culprit. This simple test saves you from buying parts you don’t need.
Step 4: Hunting for Vacuum Leaks
The large rubber intake boots between the throttle body and the engine head are notorious for developing small cracks over time. With the engine running, very carefully spray a small amount of brake cleaner or starting fluid around the base of the intake boots. WARNING: This is flammable. Do this in a well-ventilated area away from any ignition sources. If the engine RPM changes when you spray a certain spot, you’ve found your vacuum leak.
Step 5: Checking Fuel Pressure and Compression
If you’ve done all of the above and still have the codes, the problem is likely deeper. You’ll need to hook up a fuel pressure gauge to the fuel rail to ensure the pump is delivering adequate pressure (check your service manual for the exact spec).
Finally, a compression test will tell you about the mechanical health of the engine. If one cylinder has significantly lower compression than the other, it points to an internal issue like worn piston rings or a valve problem. At this point, it might be time to consult a trusted professional mechanic.
Best Practices for Prevention: A Solid Care Guide
The best way to fix a problem is to prevent it from happening. Following a good 2017 polaris rzr showing codes 65590 and 65591 care guide will save you headaches down the road. The benefits of 2017 polaris rzr showing codes 65590 and 65591 prevention are clear: more ride time and less wrench time.
- Use Quality Fuel: Stick to high-quality, top-tier gasoline. Avoid letting fuel sit in the tank for months without a stabilizer.
- Change Plugs Regularly: Don’t wait for a misfire. Change your spark plugs as part of your regular maintenance schedule. It’s the cheapest tune-up you can do.
- Keep Your Air Filter Clean: A clogged air filter restricts airflow, forcing the engine to run rich, which can foul spark plugs over time.
- Listen to Your Machine: Pay attention to how your RZR runs. If it starts to feel sluggish or idle rough, investigate it before it throws a code.
Following these 2017 polaris rzr showing codes 65590 and 65591 best practices isn’t just about reliability. A well-maintained, efficiently running engine uses less fuel and produces fewer emissions. This makes for a more sustainable 2017 polaris rzr showing codes 65590 and 65591 ownership experience and is a more eco-friendly 2017 polaris rzr showing codes 65590 and 65591 approach to enjoying the outdoors we all love.
Frequently Asked Questions About RZR Misfire Codes
Can I still drive my RZR with codes 65590 and 65591?
It’s highly discouraged. When a cylinder misfires, unburnt fuel can be dumped into the hot exhaust system, potentially damaging the catalytic converter. More importantly, it puts extra strain on other engine components and can lead to more severe damage. It’s best to diagnose and fix the issue before riding again.
Do I need a special scanner to read these codes?
No. One of the great things about the Polaris RZR is that the fault codes are displayed directly on the instrument cluster. You can cycle through the display to see the code number (e.g., 65590) and the occurrence count (how many times it’s happened).
What if I only have one code (e.g., just 65590)?
That’s actually great news for diagnostics! It means your problem is isolated to one specific cylinder. You can focus your attention on the spark plug, plug wire, and fuel injector for that cylinder first. The “swaptronics” test described earlier is perfect for this scenario.
Could bad gas cause these misfire codes?
Absolutely. Water in the fuel or old, degraded gasoline can definitely cause misfires. If your RZR has been sitting for a long time or you just filled up at a questionable station, you might consider draining the tank and starting with fresh, high-quality fuel before you dive into mechanical fixes.
Tackling a check engine light and diagnostic codes can feel daunting, but it’s a fantastic way to learn more about your machine and become a more self-sufficient rider. By following a logical process—checking spark, fuel, and air—you can solve the vast majority of misfire issues yourself.
Remember to work safely, take your time, and don’t be afraid to ask for help if you get stuck. Now you have the knowledge to turn those frustrating codes into a conquered challenge. Get those tools out, get that RZR purring again, and we’ll see you on the trail!
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