Polaris Sportsman 570 Code 651 5 – Your Complete DIY Diagnostic

There’s nothing that kills a weekend ride faster than a flashing check engine light. You glance down at your dash, see the dreaded polaris sportsman 570 code 651 5, and your trusty ATV is suddenly running rough—or maybe it won’t start at all. Your trail plans just hit a major roadblock.

Don’t call for a trailer just yet. That string of numbers might look intimidating, but it’s pointing you toward a very specific and often fixable problem. We’re here to tell you that with a few common tools and a bit of patience, you can likely diagnose and solve this issue right in your own garage.

This comprehensive guide will demystify the polaris sportsman 570 code 651 5, walking you through what it means, the common causes, and a step-by-step process to get your machine roaring back to life. Let’s get wrenching.

What Does Polaris Code 651 5 Actually Mean?

Think of Polaris trouble codes as a language. Your ATV’s computer, the Engine Control Unit (ECU), is trying to tell you exactly what’s wrong. The code 651 5 is a combination of two numbers: SPN 651 and FMI 5.

Let’s break it down in plain English:

SPN 651: This points directly to the Engine Fuel Injector for Cylinder #1. Since the Sportsman 570 has a single-cylinder engine, this is your one and only fuel injector.
FMI 5: This specifies the type of fault. It stands for “Current Below Normal / Open Circuit.”

So, when you put them together, your ECU is saying: “Hey, I’m trying to send power to the fuel injector, but I’m not detecting the right electrical signal. It seems like the wire is cut or the injector itself is broken!”

This electrical fault prevents the injector from spraying fuel into the engine correctly, leading to a range of noticeable symptoms.

Common Symptoms of Code 651 5

If your Sportsman is throwing this code, you’re likely experiencing one or more of these issues:

Check Engine Light (CEL): This is the most obvious sign.
Engine Misfires or Runs Rough: The engine will sputter and shake because it’s being starved of fuel.
No-Start Condition: If the injector isn’t firing at all, the engine won’t get any fuel to start.
Hard Starting: It might take a lot of cranking to get the engine to finally fire up.
Significant Loss of Power: Your ATV will feel sluggish and won’t accelerate properly.
Poor Fuel Economy: An inefficiently running engine will burn more gas.

Safety First: Before You Start Wrenching

Before you even think about picking up a tool, let’s cover some ground rules. Working on fuel and electrical systems requires care. Your safety is always priority number one.

Disconnect the Battery: Always disconnect the negative terminal of your battery first. This prevents any accidental short circuits that could damage sensitive electronics or cause a spark.
Work in a Ventilated Area: You may be exposed to gasoline fumes. Make sure you’re in a garage with the door open or outside.
No Sparks or Flames: This is a non-negotiable. Keep all sources of ignition, like cigarettes, lighters, and space heaters, far away from your work area.
Have a Fire Extinguisher Ready: Keep a Class B (rated for flammable liquids) fire extinguisher within arm’s reach. You’ll probably never need it, but you’ll be glad it’s there if you do.
Wear Safety Gear: Put on safety glasses and nitrile gloves. Fuel is nasty stuff you don’t want on your skin or in your eyes.

Essential Tools & Parts for the Job

You don’t need a professional shop to tackle this, but having the right tools makes all the difference. Here’s a list of what you’ll likely need to complete this polaris sportsman 570 code 651 5 guide.

Tools:

Digital Multimeter: This is your most important diagnostic tool. You don’t need an expensive one, but it must be able to measure Volts (DC) and Ohms (Ω).
Basic Socket & Ratchet Set: Metric sizes will be needed to remove plastics and components.
Torx Bit Set: Polaris loves using Torx fasteners.
Plastic Trim Removal Tools: To safely pop off plastic body panels without scratching them.
Flashlight or Headlamp: Good lighting is key to spotting damaged wires.
Electrical Contact Cleaner: For cleaning up grimy connectors.
Needle Nose Pliers: Helpful for manipulating small connectors and wires.

Potential Parts:

New Fuel Injector: If you determine yours has failed.
Dielectric Grease: To protect electrical connections from moisture and corrosion.
Wire, Solder, and Heat-Shrink Tubing: For making professional, long-lasting wiring repairs.

How to Diagnose Polaris Sportsman 570 Code 651 5: A Step-by-Step Guide

Alright, let’s get our hands dirty. We’re going to work from the easiest and most common causes to the more complex ones. Don’t just throw parts at the problem; a little diagnosis can save you a lot of money.

Step 1: The Visual Inspection (The 5-Minute Fix)

You’d be shocked how many electrical issues are found with a simple visual check. The fuel injector is located on the throttle body, right on top of the engine. You’ll need to remove some of the plastic covers around the seat and gas tank to get a clear view.

Locate the Injector: Find the component with a single electrical connector plugged into the top of the engine’s intake.
Check the Connector: Grab the plastic connector and wiggle it. Is it loose? Is the locking tab broken? Unplug it and look inside both ends. Do you see any green or white crusty corrosion? Are any of the metal pins bent or pushed back into the connector?
Trace the Wires: Follow the two wires coming from the injector connector as far back as you can. Look for any signs of damage. Check for spots where the harness might be rubbing against the frame, a sharp edge, or the hot engine. This is one of the most common problems with polaris sportsman 570 code 651 5.

If you find a loose connection or obvious corrosion, clean it with electrical contact cleaner, add a dab of dielectric grease, and plug it back in securely. If you find a broken wire, you’ve found your culprit. If everything looks good, move to the next step.

Step 2: Testing the Fuel Injector Itself

Now we’ll use our multimeter to see if the injector’s internal coil has failed. This is the definitive test to see if you need a new injector.

Set Your Multimeter: Turn the dial to the Ohms (Ω) setting. The 200 Ohm range is usually perfect for this.
Disconnect the Injector: Make sure the electrical connector is unplugged from the fuel injector.
Probe the Injector Pins: Touch the two multimeter probes to the two metal prongs on the fuel injector itself. The polarity doesn’t matter.
Read the Resistance: A healthy Polaris 570 fuel injector should have a resistance of approximately 12 to 15 Ohms. If your reading is within this range, your injector is likely good. If your multimeter reads “OL” (Open Loop), “1”, or a massively high number, the coil inside the injector is broken. It’s toast, and you need a new one.

Step 3: Testing the Wiring Harness

If your injector tested good, the problem is almost certainly in the wiring between the ECU and the injector. This test checks for a break in those wires.

Key On, Engine Off: Turn the ignition key to the “ON” position but do not start the engine.
Set Multimeter to DC Volts: Switch your multimeter to the DC Volts setting (V⎓).
Test for Power: Probe the two terminals inside the wiring harness connector (not the injector). You should see a voltage reading, typically around 12 volts (or whatever your battery voltage is). One wire is power, and the other is the ground signal from the ECU.
Check for Continuity (Advanced): If you don’t have power, you’ll need to check the continuity of each wire from the injector plug back to the ECU. This involves finding the correct pins on the main ECU connector, which can be found in a factory service manual. Set your multimeter to the continuity setting (it usually has a sound symbol). A good wire will make the meter beep. This confirms the wire is intact from end to end.

The Fix: Repairing Wires and Replacing the Injector

Once you’ve pinpointed the problem, it’s time for the repair. Here are some polaris sportsman 570 code 651 5 best practices for getting it done right.

How to Replace the Fuel Injector

If your injector failed the resistance test, replacement is straightforward.

Relieve Fuel Pressure: Loosen the gas cap to vent the tank pressure.
Remove the Fuel Rail: The injector is held in place by the fuel rail. Unscrew the bolts holding the fuel rail to the engine.
Swap the Injector: Gently pull the fuel rail up. The injector will likely come with it. Pull the old injector out of the rail. Lightly lubricate the new injector’s O-rings with a bit of clean motor oil and pop it into place.
Reassemble: Reinstall the fuel rail, tighten the bolts, and plug in the electrical connector.

Best Practices for Wiring Repairs

Found a broken wire? Don’t just twist them together and wrap them in tape. Do a sustainable polaris sportsman 570 code 651 5 repair that will last.

Solder and Heat-Shrink: The best method is to strip the wires, solder them together for a strong electrical connection, and then slide a piece of heat-shrink tubing over the repair to make it waterproof and durable.
Avoid Crimp Connectors: Cheap, unsealed butt connectors are prone to corrosion and failure, especially on an off-road machine. If you must use one, use a high-quality, heat-shrink-style crimp connector.
Add Protection: If the wire chafed on the frame, re-route it slightly or wrap that section of the harness in split-loom tubing or high-quality electrical tape to prevent it from happening again. This is a key part of any good polaris sportsman 570 code 651 5 care guide.

Clearing the Code and Final Checks

After your repair, it’s time to verify the fix. Reconnect your battery’s negative terminal.

Turn the key to the “ON” position. In many cases, after a few successful start-and-run cycles, the ECU will see that the fault is gone and the check engine light will turn off on its own.

Before you celebrate, turn the key on and listen for the fuel pump to prime. Carefully inspect your work area, especially around the fuel rail if you replaced the injector, for any signs of fuel leaks. The benefits of fixing polaris sportsman 570 code 651 5 correctly include restored power and, importantly, a safe fuel system.

A proper repair is also an eco-friendly polaris sportsman 570 code 651 5 solution. A correctly functioning injector ensures a complete burn of fuel, reducing harmful emissions and improving your gas mileage on the trail.

Frequently Asked Questions About Polaris Sportsman 570 Code 651 5

Can I still ride my Sportsman with code 651 5?

It is strongly not recommended. At best, you’ll have very poor performance and could get stranded. At worst, running the engine in a lean or inconsistent fuel condition could potentially cause internal damage over time.

How much does it cost to fix code 651 5?

The cost varies greatly depending on the cause. If it’s a simple wiring issue you can fix yourself, the cost could be next to nothing. If you need a new OEM fuel injector, expect to pay between $100 and $150 for the part, plus labor if you take it to a shop.

Is this a common problem on the Sportsman 570?

Yes, wiring and connector issues can be fairly common on any ATV, including the Sportsman 570. The constant vibration, exposure to mud, water, and debris puts a lot of stress on the electrical system, making it a frequent source of problems.

What if I fix it and the code comes back?

If the code returns immediately, double-check your work. Ensure your wiring repair is solid or that the injector connector is fully seated. If the problem persists after you’ve confirmed the injector and wiring are good, you may have a very rare issue with the injector driver circuit in the ECU, which would likely require a professional diagnosis.

Tackling a diagnostic code like this can feel daunting, but by following a logical process—inspect, test, then repair—you can solve the problem and gain valuable experience working on your machine. You’ve just saved yourself a trip to the dealer and earned some serious garage cred.

Now, button up those plastics, check your work one last time, and get back out on the trail. You’ve earned it!

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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.