Polaris Sportsman 700 Code 45 - Your Complete DIY Diagnostic & Repair

There’s nothing quite like the sinking feeling you get miles from the trailhead. Your trusty Polaris Sportsman 700 starts to sputter, the check engine light flashes, and the dash blinks a cryptic message: Fault Code 45. It’s a moment that can turn a perfect day of riding into a frustrating session of head-scratching.

You’ve been there, right? An unexpected code that threatens to sideline your machine and your weekend.

But what if I told you that you can solve this problem yourself? I promise this guide will demystify the polaris sportsman 700 code 45, walk you through a professional-level diagnosis with basic tools, and show you exactly how to get your ATV running smoothly again.

We’ll cover what this code means, the tools you’ll need, a step-by-step process to pinpoint the failure, and the best practices to keep it from happening again. Let’s get you back on the trail.

What Exactly is a Polaris Sportsman 700 Code 45?

First things first, let’s translate that code. On a Polaris Sportsman 700, fault code 45 points directly to an issue with the Barometric Air Pressure (BAP) Sensor Circuit. It means the signal from the sensor to the Engine Control Unit (ECU) is either too high or too low.

Think of the BAP sensor as your ATV’s weatherman. Its only job is to measure the atmospheric pressure of the air around you. It then sends this information to the ECU, your ATV’s brain.

The ECU uses this data to make tiny adjustments to the fuel-to-air mixture. This ensures your engine runs efficiently whether you’re riding at sea level or climbing a mountain pass. When the BAP sensor fails, the ECU gets bad information and can’t properly manage the fuel, leading to a host of performance issues.

Symptoms of a Failing BAP Sensor

Beyond the check engine light, a faulty BAP sensor often causes noticeable problems. You might experience:

Hard Starting: The engine struggles to turn over, especially when cold.
Rough Idle: The engine sputters or idles erratically.
Loss of Power: Your ATV feels sluggish and doesn’t have its usual snap.
Poor Fuel Economy: You’re burning through gas much faster than normal.
Black Smoke from Exhaust: This is a classic sign of a rich fuel mixture, as the ECU is dumping too much gas into the engine.

Understanding these symptoms is the first step in our comprehensive polaris sportsman 700 code 45 guide. Now, let’s gather the tools to confirm our diagnosis.

Tools and Gear You’ll Need for the Job

You don’t need a full professional shop to tackle this job. Most of what you’ll need is probably already in your toolbox. Having everything ready beforehand makes the process smooth and efficient.

Basic Hand Tools: A good metric socket set, a set of combination wrenches, and assorted screwdrivers are essential for any work on your machine.
Digital Multimeter: This is the most important tool for this diagnosis. You don’t need a high-end model; a basic one that can read DC Voltage and resistance will work perfectly.
T-25 Torx Driver or Bit: The BAP sensor is typically held in place by a single T-25 Torx screw.
Electrical Contact Cleaner: A spray can of this will help you clean connections without leaving a residue.
Dielectric Grease: This non-conductive grease is crucial for protecting electrical connections from moisture and corrosion.
Safety Gear: Always wear safety glasses and a pair of mechanic’s gloves.

Step-by-Step Diagnostic Guide: How to Polaris Sportsman 700 Code 45

Alright, let’s get our hands dirty. Follow these steps methodically, and you’ll find the source of your code 45. This process is designed to check the easiest and most common culprits first. Don’t skip steps!

Step 1: Locate the BAP Sensor

Before you can test it, you have to find it. On the Polaris Sportsman 700 EFI models, the BAP sensor is a small, black plastic sensor typically mounted on or very near the throttle body assembly. It will have a three-wire electrical connector plugged into it.

You may need to remove the seat and a side plastic panel to get a clear view and good access to the area around the airbox and throttle body.

Step 2: Perform a Thorough Visual Inspection

Many electrical problems are simply due to a bad connection. Before grabbing your multimeter, take a close look at the sensor and its wiring. This is one of the most common problems with polaris sportsman 700 code 45.

Check the Wiring Harness: Carefully trace the three wires coming from the sensor. Look for any signs of damage—chafing, cracking, melting, or breaks. Wires can get rubbed raw against the frame over time.
Inspect the Connector: Unplug the connector from the sensor. Look inside both ends. Do you see any green or white crusty corrosion? Are any of the metal pins bent, broken, or pushed back into the connector?
Examine the Sensor Body: Check the plastic housing of the sensor itself for any cracks or physical damage.

If you find a damaged wire or a corroded connector, you may have already found your problem. Repair the wire or clean the connector thoroughly before proceeding.

Step 3: Test the Circuit with a Multimeter

If the visual inspection looks good, it’s time to confirm whether the sensor or the circuit is faulty. This is where your multimeter becomes your best friend. Set it to read DC Volts.

The three wires on the BAP sensor connector serve specific functions. While colors can vary slightly by year, they are generally:

5-Volt Reference: The ECU sends 5 volts to power the sensor.
Ground: The return path for the electrical circuit.
Signal: The sensor sends a variable voltage signal back to the ECU based on air pressure.

Here’s how to polaris sportsman 700 code 45 test the circuit:

Test for Reference Voltage: With the connector unplugged, turn the ignition key to the ON position (do not start the engine). Touch the red probe of your multimeter to the terminal for the 5V reference wire and the black probe to a good ground on the engine or frame. You should see a reading of approximately 5 volts. If you don’t, the problem is in the wiring going back to the ECU, or the ECU itself.
Test the Ground Wire: Switch your multimeter to the continuity or resistance (Ohms Ω) setting. Touch one probe to the ground wire’s terminal and the other to the negative battery terminal. You should get a reading of near zero ohms, indicating a good ground connection.
Test the Signal Output (Optional but informative): If the reference and ground are good, the sensor itself is the prime suspect. With the sensor plugged in, you can carefully back-probe the signal wire. The voltage reading will vary with altitude, but a completely dead sensor will often read 0 volts or a stuck 5 volts, neither of which is correct.

If you have a solid 5V reference and a good ground, but the code persists, the BAP sensor has almost certainly failed.

The Fix: Replacing Your BAP Sensor

If your diagnosis points to a bad sensor, the good news is that replacement is very simple. The benefits of polaris sportsman 700 code 45 repair are immediate: your ATV will run smoother, have more power, and be more reliable.

Disconnect the Battery: Before starting any electrical replacement, always disconnect the negative terminal of your battery as a safety precaution.
Unplug the Electrical Connector: Carefully press the release tab and pull the connector off the old sensor.
Remove the Old Sensor: Use your T-25 Torx driver to remove the single screw holding the sensor in place. The sensor should now lift straight out.
Install the New Sensor: Seat the new BAP sensor in place and tighten the Torx screw. Be careful not to overtighten it—just snug is fine.
Protect the Connection: Apply a small dab of dielectric grease to the inside of the electrical connector. This is a crucial step in any good polaris sportsman 700 code 45 care guide as it prevents future moisture and corrosion issues.
Reconnect and Reset: Plug the connector firmly onto the new sensor and reconnect your battery terminal. The fault code may clear on its own after a few minutes of runtime. If not, disconnecting the battery for 15-20 minutes will often reset the ECU and clear the stored code.

Best Practices to Prevent Future Sensor Issues

An ounce of prevention is worth a pound of cure, especially when it comes to your ATV’s electronics. Following these polaris sportsman 700 code 45 best practices can save you headaches down the road.

The best approach is a sustainable polaris sportsman 700 code 45 maintenance plan. Whenever you’re doing routine maintenance like an oil change or air filter cleaning, take five extra minutes to inspect key wiring harnesses. Look for areas where wires might be rubbing against the frame.

After washing your ATV or riding in very wet conditions, consider pulling apart a few key connectors (like the BAP, TPS, and ECU connectors) and ensuring they are dry. Applying dielectric grease periodically is a cheap and effective way to ensure a long, corrosion-free life for your electrical system.

Frequently Asked Questions About Polaris Sportsman 700 Code 45

Can I still ride my Sportsman 700 with code 45 active?

It’s not recommended for any extended period. The ATV will likely run in a “limp mode” with a rich fuel mixture. Continuing to ride this way can foul your spark plugs, dilute your engine oil with unburnt fuel, and potentially cause long-term damage to your engine and exhaust.

How much does a new BAP sensor cost?

Prices can vary, but you can typically expect an OEM (Original Equipment Manufacturer) BAP sensor to cost between $60 and $100. Aftermarket options may be available for less, but for critical electronic components, we at FatBoysOffroad always recommend sticking with OEM parts for the best reliability.

What if I replaced the sensor and the code 45 comes back?

If a new sensor doesn’t fix the problem, the issue is almost certainly in the wiring harness between the sensor and the ECU. Go back and re-check the 5V reference and ground signals. You may have an intermittent break in a wire that only shows up when the machine is vibrating. A professional technician may be needed to trace the harness and find the fault.

Tackling an engine code can feel intimidating, but as you’ve seen, the polaris sportsman 700 code 45 is a very manageable DIY repair. By following these steps, you’ve not only saved yourself a trip to the dealer but also gained a deeper understanding of how your machine works.

Now you have the knowledge and confidence to diagnose and fix this common issue. So grab your tools, get that sensor swapped, and get back to what matters most. Wrench safe, ride hard, and we’ll see you out 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.