That dreaded check engine light flashing on your 2016 Polaris RMK 800’s dash can instantly sink your heart and ruin a perfect powder day. You’re deep in the backcountry, the engine suddenly feels sluggish, and a cryptic number is staring back at you from the gauge cluster. What now?
You’ve come to the right place. That 2016 Polaris RMK 800 520335 code might seem intimidating, but it points to a very specific and common issue. We promise to guide you through exactly what this code means and, more importantly, how you can diagnose and fix it yourself, saving you a hefty bill and a long wait at the dealership.
In this comprehensive guide, we’ll break down the technical jargon, show you the most common culprits, provide a step-by-step troubleshooting plan for any DIY skill level, and share pro tips to get you back on the snow fast. Let’s get that sled running right.
What is the 2016 Polaris RMK 800 520335 Code, Really?
Before you start throwing wrenches and replacing parts, it’s crucial to understand what your sled is trying to tell you. This isn’t just a random number; it’s a specific message from your engine’s computer, the ECU (Engine Control Unit).
Decoding the SPN and FMI System
Polaris uses a diagnostic system with two key parts: the SPN and the FMI.
- SPN (Suspect Parameter Number): This tells you which component or system is having a problem. In your case, SPN 520335 points directly to the Exhaust Gas Temperature (EGT) Sensor on the MAG (magneto) side cylinder.
- FMI (Failure Mode Identifier): This number, which appears after the SPN, tells you how the component is failing. Common FMIs for this code include 3 (voltage too high) or 4 (voltage too low).
Knowing both numbers is key. For example, 520335 / 4 tells a much more specific story than 520335 alone. Always write down the full code displayed on your gauge.
The Critical Role of the EGT Sensor
Your RMK 800 has two EGT sensors, one for each cylinder (MAG and PTO side). These sensors act like thermometers, constantly measuring the temperature of the exhaust gases leaving the engine.
This data is vital. The ECU uses it to make real-time adjustments to the fuel mixture and timing, protecting the engine from running too lean (hot) or too rich (cold). A faulty sensor sends bad data, causing the ECU to make poor decisions, which can lead to reduced performance and, in worst-case scenarios, engine damage.
Common Symptoms You Can’t Ignore
When the 520335 code pops up, it’s usually not alone. You’ll likely experience one or more of these symptoms:
- Check Engine Light (CEL): This is the most obvious sign.
- Limp Mode: The sled will feel gutless as the ECU intentionally reduces power to protect the engine.
- Bogging or Hesitation: The engine may run rough, especially under load.
- Poor Fuel Economy: The ECU might be dumping extra fuel to be safe, draining your tank faster.
- Difficulty Starting: An engine running on bad data can be hard to start, hot or cold.
Tools and Safety First: Prepping for the Job
Before you dive in, gather the right tools and get your workspace ready. A little preparation makes the job smoother and safer. This is one of the most important 2016 polaris rmk 800 520335 code tips we can offer.
Essential Tools:
- Basic metric socket and wrench set (8mm, 10mm, etc.)
- Torx bit set
- A good quality digital multimeter
- Electrical contact cleaner
- Zip ties and side cutters
- Dielectric grease
- A clean rag
Safety Precautions:
- Let It Cool Down: The exhaust system gets extremely hot. Always work on a cold engine to avoid serious burns.
- Disconnect the Battery: Disconnect the negative battery terminal to prevent any accidental electrical shorts.
- Work in a Well-Lit Area: Good lighting is your best friend for spotting frayed wires or corrosion.
- Remove the Side Panels: Take off the right-side panel and pipe shield to get clear access to the MAG-side EGT sensor and its wiring.
How to Diagnose the 2016 Polaris RMK 800 520335 Code: A Step-by-Step Guide
Now for the hands-on part. Follow these steps methodically. Do not skip ahead, as the simplest fix is often the one we overlook. This is the ultimate how to 2016 polaris rmk 800 520335 code diagnostic process.
Step 1: The Visual Inspection (The 5-Minute Check)
Your eyes are your most powerful diagnostic tool. Start at the EGT sensor, which is threaded into the exhaust pipe (Y-pipe) on the right (MAG) side of the engine.
Follow the wire from the sensor all the way back to its connector. Look for:
- Burnt or Melted Wires: Is the wire touching the hot exhaust pipe?
- Chafed or Rubbed Wires: Check where the harness runs along the frame or near other components. Vibration can rub through the insulation.
- Pinched Wires: Ensure the harness isn’t caught between the frame and a panel.
- Obvious Breaks: A clean break in the wire is an easy find.
Many times, the problem is a simple wiring issue caused by improper routing from the factory or a previous repair.
Step 2: Check and Clean the Connections
If the wiring looks okay, the next stop is the electrical connector. Find where the EGT sensor harness plugs into the main sled harness.
Unplug the connector and inspect the pins and sockets on both sides. Look for any signs of green or white corrosion, which indicates water intrusion. Even if it looks clean, spray both sides with electrical contact cleaner and let it dry completely. Apply a small amount of dielectric grease to the seal before reconnecting to keep moisture out. This simple step is one of the key 2016 polaris rmk 800 520335 code best practices.
Step 3: The “Sensor Swap” Trick (The Definitive DIY Test)
This is the single best way for a DIYer to confirm if the sensor itself is bad or if the problem lies in the sled’s wiring. It requires no special tools other than a wrench.
- Locate Both Sensors: You’ve already found the MAG-side sensor. The PTO-side sensor is in the identical position on the left side of the engine.
- Unplug Both Sensors: Disconnect the electrical connectors for both the MAG and PTO EGT sensors.
- Swap the Connections: Plug the MAG-side sensor’s wire into the PTO-side’s connection on the main harness. Then, plug the PTO-side sensor’s wire into the MAG-side’s connection. You are not moving the sensors themselves, just swapping where their wires plug in.
- Start the Sled: Fire up the engine and see what code appears.
Interpreting the Results:
- If the code changes to the PTO-side EGT sensor code (SPN 520336), you’ve found your culprit! The problem followed the sensor, which means the MAG-side EGT sensor is bad.
- If the code stays as 520335 (MAG side), the sensor is likely fine. The problem is in the wiring harness between the connector and the ECU.
Step 4: Testing the Wiring Harness (For Advanced DIYers)
If the sensor swap test points to a wiring issue, you’ll need a multimeter to check for continuity. This involves checking for a solid connection from the sensor plug all the way to the ECU plug. This is a more advanced step, and if you’re not comfortable with wiring diagrams and multimeter use, this is a good point to consider professional help.
Common Problems & Solutions for Code 520335
Based on the diagnostic steps above, you’ll land on one of two primary issues. Here’s a breakdown of the common problems with 2016 polaris rmk 800 520335 code and how to fix them.
Problem: A Failed EGT Sensor
If your sensor swap proved the sensor is faulty, the fix is straightforward: replacement. EGT sensors live in a harsh environment of extreme heat and vibration, and they eventually fail.
Simply purchase a new OEM or quality aftermarket EGT sensor. Let the exhaust cool completely, unscrew the old sensor from the Y-pipe, apply a small amount of anti-seize compound to the threads of the new sensor (be careful not to get any on the tip), and install it. Plug it in, and you’re good to go.
Problem: A Damaged Wiring Harness
This is often the more frustrating issue. If the code didn’t move during the sensor swap, you have a break, short, or poor connection somewhere in the harness.
Carefully re-inspect the entire length of the wire from the connector back. A common chafe point is where the harness routes over the engine or along the frame. If you find a damaged section, you can repair it by carefully soldering the wires and protecting the repair with heat-shrink tubing. Ensure you route the repaired harness away from heat sources and sharp edges, using zip ties to secure it.
When to Call a Pro: Knowing Your Limits
There is no shame in calling for backup. If you’ve performed the visual checks and the sensor swap but can’t find the wiring issue, or if you’re uncomfortable with electrical diagnostics, it’s time to take it to a qualified technician. They have advanced tools and experience to trace the fault quickly, saving you hours of frustration.
Best Practices for EGT Sensor Care and Prevention
An ounce of prevention is worth a pound of cure. Following this simple 2016 polaris rmk 800 520335 code care guide can help you avoid this issue in the future.
Proactive Wiring Inspection
Every time you have the side panels off for pre-season prep or maintenance, take two minutes to inspect the EGT sensor harnesses. Make sure they are secure, not rubbing on anything, and away from the hot pipe. A well-placed zip tie can save you a huge headache on the trail.
The Importance of Proper Routing
If you ever remove the exhaust, pay close attention to how the sensor wires are routed. Reinstall them exactly the same way. Improper routing is the #1 cause of harness damage.
A Note on Eco-Friendly and Sustainable Repairs
Tackling this job yourself is inherently a sustainable 2016 polaris rmk 800 520335 code practice. By properly diagnosing the issue, you replace only the failed part. This avoids the waste of “parts cannon” repairs where good components are thrown away. Furthermore, a properly functioning EGT system ensures your engine runs at peak efficiency, which is a more eco-friendly 2016 polaris rmk 800 520335 code solution that reduces emissions and conserves fuel.
Frequently Asked Questions About the 2016 Polaris RMK 800 520335 Code
Can I still ride my sled with code 520335 active?
You can, but it’s not recommended for long. The sled will be in limp mode, meaning you’ll have significantly reduced power. More importantly, the ECU is guessing at the fuel mixture, which could potentially lead to long-term engine damage if you continue to ride it hard.
How much does it cost to fix this code?
The cost varies greatly. If it’s a simple wiring fix you do yourself, the cost could be virtually zero. A new EGT sensor typically costs between $100-$150. If you take it to a dealer, you can expect to pay for 1-2 hours of diagnostic labor plus the cost of parts, potentially running into several hundred dollars.
Is the MAG side EGT sensor the same as the PTO side?
Yes, on the 2016 RMK 800, the sensors for the MAG and PTO sides are identical parts. This is what makes the “sensor swap” diagnostic trick so effective and easy to perform.
Will clearing the code fix the problem?
No. Clearing the code without fixing the underlying issue is like turning off your smoke alarm while the fire is still burning. The code will come right back as soon as the ECU detects the same fault, usually within seconds of starting the engine.
Tackling a check engine light can be daunting, but with this 2016 polaris rmk 800 520335 code guide, you’re now equipped with the knowledge to diagnose and solve the problem like a pro. By working methodically—inspecting the wiring, checking connections, and performing the sensor swap—you can pinpoint the exact cause and get the job done right.
Now you have the confidence and the know-how to handle this common code. Get those tools out, stay safe, and get ready to enjoy the deep powder once again. Happy riding!
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