There’s nothing that stops the fun or the work day faster than a glowing check engine light on your dash. You glance down at your 2018 Polaris Ranger 900 Crew, and it’s flashing code 746. To make things worse, the radiator fan is running full blast and won’t shut off, even if the engine is cold.
You’re probably thinking about a costly trip to the dealership, but take a breath. This is one of the most common codes on these machines, and you can absolutely diagnose and fix it yourself with basic tools.
We promise this guide will give you the confidence and the step-by-step instructions to solve the problem. We’ll break down exactly what the 2018 polaris ranger 900 crew code 746 means, how to test the components, and how to get your Ranger running right again. Let’s get those tools out and get to work.
What is Fault Code 746 and Why is it on Your Ranger?
First things first, let’s decode the message your Ranger is sending you. Fault Code 746 is specifically tied to the Engine Coolant Temperature (ECT) sensor circuit. The technical definition is “ECT Sensor: Shorted to Ground / Below Normal Operating Range.”
In simple terms, your Ranger’s main computer (the ECU) is getting a signal from the sensor that is impossibly low. It thinks the engine is running at an arctic temperature, like -40°F. This is almost always an electrical fault, not an actual cooling problem.
When the ECU sees this faulty signal, it triggers a failsafe mode to protect your engine. The most common symptoms you’ll notice are:
- The Check Engine Light (CEL) is illuminated on your dashboard.
- The radiator fan runs constantly as soon as you turn the key on. The ECU does this because it can’t trust the temperature reading, so it runs the fan to prevent any chance of overheating.
- You might experience slightly rough running or poor fuel economy because the ECU is adjusting the fuel mixture based on bad data.
The most frequent culprits for this code are a bad ECT sensor itself or damaged wiring leading to it. Luckily, both are straightforward to check.
Essential Tools and Safety Precautions for This Job
Before you dive in, let’s get your gear in order. Having the right tools makes the job smooth and safe. You don’t need a professional shop, just a few key items.
Required Tools:
- A basic socket set with a deep well socket (typically 19mm for the sensor).
- A digital multimeter. This is the most crucial tool for this diagnosis.
- Needle-nose pliers.
- A small wire brush or contact cleaner.
- Dielectric grease for reassembly.
- A drain pan and some shop towels.
- A new ECT sensor (if your old one tests bad). Part numbers can vary, so check with your dealer or a reliable parts supplier for your specific VIN.
Safety First, Always:
Working on a cooling system requires caution. Coolant is hot and pressurized when the engine is running. Always follow these rules.
First, ensure the engine is completely cool to the touch. Never open a radiator cap or remove a coolant sensor on a warm engine. Second, disconnect the negative terminal from your battery to prevent any electrical shorts. Finally, wear safety glasses and gloves.
Step-by-Step 2018 Polaris Ranger 900 Crew Code 746 Guide
Alright, let’s get to the heart of it. Follow these steps methodically, and you’ll pinpoint the problem. This is the core of our 2018 polaris ranger 900 crew code 746 guide, designed for the careful DIYer.
Step 1: Locate the Engine Coolant Temperature (ECT) Sensor
You can’t fix what you can’t find. On the Polaris ProStar 900 engine, the ECT sensor is typically located on the cylinder head, very close to the thermostat housing where the main radiator hose connects to the engine.
It’s a small, brass-colored sensor with a two-wire electrical connector plugged into it. You may need to lift the dump bed to get clear access to it.
Step 2: Perform a Visual Inspection of Wiring and Connectors
Many electrical gremlins are found with a simple visual check. Unplug the connector from the sensor. It has a small tab you’ll need to press to release it.
Carefully inspect both the sensor pins and the inside of the electrical connector. Look for any green or white crusty corrosion, bent pins, or dirt. Also, trace the wires back as far as you can, looking for any signs of damage—like rubbing against the frame, melting, or evidence of rodents chewing on them. This is one of the most common problems with 2018 polaris ranger 900 crew code 746.
If you find corrosion, clean it thoroughly with a small wire brush or electrical contact cleaner. Sometimes, just cleaning and re-seating the connector is enough to fix the issue.
Step 3: Test the ECT Sensor with a Multimeter
This is the definitive test. It will tell you if the sensor itself has failed. Set your digital multimeter to the Ohms (Ω) setting, usually in the 20k range.
- With the sensor unplugged, touch the two multimeter probes to the two metal pins on the ECT sensor itself.
- On a cold engine (around 68°F / 20°C), you should see a resistance reading somewhere between 2,000 and 3,000 Ohms. The exact value isn’t critical, but it should be in that ballpark.
- Here’s the key for Code 746: If you get a reading of nearly zero Ohms or just a few Ohms, the sensor is internally shorted. This is a failed sensor, and it needs to be replaced.
Step 4: Test the Wiring Harness for a Short
If your sensor tested good in the previous step, the problem is likely in the wiring harness. This test checks if one of the wires is shorted to the vehicle’s frame.
- Keep the harness unplugged from the sensor. Turn the vehicle’s key to the “ON” position (do not start it).
- Set your multimeter to measure DC Volts.
- Connect the black (negative) probe of your multimeter to a good chassis ground, like the negative battery terminal or a clean bolt on the frame.
- Carefully touch the red (positive) probe to each of the two metal contacts inside the wiring connector.
- One wire should show around 5 volts (this is the reference voltage from the ECU). The other wire is the signal return and should show close to 0 volts. If both wires show 0 volts, or if the signal wire shows a solid ground connection, you have a short in the harness that needs to be repaired.
How to Replace the ECT Sensor on Your Polaris Ranger 900
If your diagnosis pointed to a bad sensor, replacing it is a quick job. This is the most common “how to 2018 polaris ranger 900 crew code 746” solution.
- Confirm the Engine is Cold: We can’t stress this enough. Safety first.
- Prepare for Spillage: Place your drain pan and a few shop towels directly below the sensor. A small amount of coolant will leak out when you remove it.
- Remove the Old Sensor: With the electrical connector already unplugged, use a deep well socket (usually 19mm) to unscrew the old sensor. Turn it counter-clockwise.
- Install the New Sensor: Have the new sensor ready to go. As soon as the old one is out, quickly thread the new one in by hand to minimize coolant loss. Ensure its sealing washer is in place.
- Tighten Correctly: Snug the sensor down with your socket. Don’t overtighten it—just tight enough to seal. The brass threads can be damaged easily.
- Reconnect and Protect: Apply a small amount of dielectric grease to the connector pins to prevent future corrosion. Plug the electrical connector back in until it clicks.
- Top Off Coolant: Check your coolant reservoir and top it off with the correct Polaris-spec fluid to replace what was lost.
Best Practices and Care Guide After the Fix
Finishing the repair is great, but ensuring it lasts is even better. Following these 2018 polaris ranger 900 crew code 746 best practices will keep your machine running smoothly.
Clearing the Code and Verifying the Repair
After reconnecting your battery, the fault code should clear itself after one or two complete run cycles (starting, warming up, and shutting down). Start the engine and let it idle. Watch to see if the fan now stays off until the engine reaches operating temperature, then cycles on and off as it should. This confirms your repair was successful.
Long-Term Coolant System Health
The benefits of 2018 polaris ranger 900 crew code 746 repair go beyond just turning off a light. A working ECT sensor ensures proper engine performance, optimal fuel efficiency, and prevents unnecessary wear on your fan motor. Always use the recommended coolant for your machine and check the level periodically as part of your regular 2018 polaris ranger 900 crew code 746 care guide.
Sustainable and Eco-Friendly Coolant Disposal
Engine coolant (ethylene glycol) is highly toxic to pets and wildlife. Practice sustainable 2018 polaris ranger 900 crew code 746 maintenance by capturing any spilled coolant in your drain pan. Do not pour it on the ground or down a drain. Most auto parts stores and local recycling centers accept used coolant for free, ensuring it’s handled in an eco-friendly 2018 polaris ranger 900 crew code 746 manner.
Frequently Asked Questions About the Polaris Ranger Code 746
Can I still drive my Ranger with code 746 active?
While the machine will likely run, it’s not recommended for extended periods. The constant fan operation is a failsafe, but the ECU is working with bad data, which can affect fuel delivery and long-term engine health. It’s best to address the issue as soon as possible.
What if I replace the sensor and the code comes back immediately?
If a new sensor doesn’t fix the problem, it almost certainly confirms the issue is in the wiring harness. You’ll need to meticulously trace the two wires from the sensor connector back toward the ECU, looking for a spot where a wire’s insulation has rubbed through and is touching the metal frame, causing a short to ground.
How much does a new ECT sensor cost?
This is one of the best parts of this DIY repair. A high-quality OEM or aftermarket ECT sensor is typically very affordable, often costing between $20 and $50. This makes it a very low-cost fix compared to a dealer service bill.
Tackling an electrical code like this can feel intimidating, but by following these steps, you’ve empowered yourself to solve the problem. You’ve saved money, learned more about your machine, and gained valuable diagnostic skills. Now you can get back to what the Ranger was built for—work and adventure. Stay safe on the trails!
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