Why Is Polaris Ranger Code 84 Flashing? [5 Reasons]

Some unprecedented things can happen with your Polaris Ranger anytime. When code 84 flashes on the dashboard, it can take time to determine how to fix the issue.

Here, we’ll look at five possible reasons behind flashing Polaris Range code 84.

A bad speed sensor, malfunctioning ECU, and misfiring cylinders are the main reasons behind the error code appearing. Also, low battery voltage and a low fuel level can make the code flash. All you have to do is solve the specific matters, and the machine will be good to go. 

Let’s focus on what is more important, the necessary solutions; keep reading to find the appropriate fixes. 

What Is Polaris Ranger Code 84?

Polaris Ranger 0 84 2 Code Speed Sensor

Polaris Ranger Code 84 is a safety alert indicating that the rider should reduce speed and check for obstacles in the path. This code indicates a malfunction or failure in the vehicle’s anti-lock braking system (ABS), mainly due to bad speed sensors.

This system is designed to help the rider maintain control of the ATV in the event of sudden stops. If the control mechanism is not working, the error code 84 flashes.

It is recommended to contact the ATV dealer as soon as the code flashes. 

What Are Polaris Ranger Codes – 2 84 1, 1 84 19, 0 84 2, 19 84 2, 84 2?

Polaris RZR Engine code 2-84 -1

Code 84 indicates issues with the speed sensors. The other numbers with the code provide more specific details, such as voltage issues, abnormal frequency, or pulse with acceleration.

The codes listed above are as follows:

  • 2 84 1/1 84 19 – Indicates an error in the crank position sensor.
  • 84 2/19 – Indicates an error in the cam position sensor.
  • 19 84 2/84 2 – Indicates an error in the throttle position sensor.

Alongside the speed sensor problems, there are four more reasons why code 84 can flash on your Polaris Ranger. 

5 Reasons Behind Polaris Ranger Flashing Code 84

Polaris Ranger, the most popular recreational off-road vehicle, is known for its performance and durability. However, if code 84 flashes, know the reasons below. 




Bad Speed SensorTransmission IssuesReplace The Speed Sensor
Malfunctioning ECULagging Engine PerformanceRepair Or Replace The ECU
Cylinder MisfireRough IdlingReplace Spark Plug, Fuel Injector, Or Ignition Coil
Low Battery VoltageCorroded Or Loosened ConnectionsSecure The Battery Connection And Lubricate Or Replace It
Low Fuel LevelsEngine Not Burning Fuel AdequatelyReplace The Fuel Pump

Although no specific information is reported, these issues can appear on any of the Polaris Ranger models from 2013 to 2019. 

Reason 1: Bad Speed Sensor

The main cause of bad speed sensors on ATVs is wear and tear. Over time, the sensor will become less sensitive and accurate, leading to several problems, such as decreased performance or a total loss of power.

Other causes of bad-speed sensors include water damage, electrical shorts, and physical damage.

Symptom: Transmission Issues

Bad speed sensors on ATVs can cause all sorts of problems with the transmission. If the sensor is not working correctly, it can erratically prevent the ATV from shifting gears. This can be dangerous, especially when riding in a rough or bumpy area. 

Solution: Replace The Speed Sensor

To replace the speed sensor, follow a process by breaking down separate actions. 

This is how it goes:

  • First, locate the old speed sensor. It is usually located near the wheel and is typically a small, cylindrical object. 
  • Once you have located it, use a good-quality socket wrench from a set to loosen the sensor’s bolt. 
  • Once the bolt is loose, use that socket wrench to remove the sensor. 
  • Be careful not to damage the sensor. If needed, use a screwdriver to pry the sensor from its housing.

When installing a new sensor, refer to the manufacturer’s instructions for the proper installation procedure. You can use the screwdriver and wrench to tighten the bolts so that the new speed new sensor is placed right the way instructed. 

Reason 2: Malfunctioning ECU

When code 84 appears, there can also be an issue with the ECU. An ECU can malfunction due to a fault in the circuitry due to age, wear and tear, or damage. 

The Engine Control Unit (ECU) is connected to the vehicle’s speed sensors via the CAN bus. The CAN bus is a communication network that connects the sensors and controllers in a vehicle.

When the ECU malfunctions, it can cause the speed sensors to become inaccurate or malfunction. This can lead to inaccurate readings, cause the vehicle to experience poor performance, or even become inoperable.

Symptom: Lagging Engine Performance

The ECU controls various aspects of the engine’s performance, including fuel delivery, ignition timing, and more. When the ECU malfunctions, it can cause problems with any or all of these systems, leading to a significant decrease in engine performance.

Solution: Repair Or Replace The ECU

For the repairs, you will need to remove the ECU from the vehicle, disassemble it, clean it and test it, and then reassemble it and install it back in the vehicle.

Here is what you need to do:

  • Remove the ECU from the vehicle: Turn off the ignition, disconnect the negative battery cable, and locate the ECU. Unplug the connectors and carefully remove the ECU from the vehicle. 
  • Disassemble the ECU: Carefully open the ECU casing and remove all the components. Use an appropriate tool to unscrew the board from its housing.
  • Clean the ECU: Use a soft brush to gently clean off any dust or dirt from the surface of the ECU. Use a can of compressed air to remove any remaining debris. (our pick: Falcon Compressed Gas)
  • Test the ECU: Connect the ECU to a testing device and run a diagnostic test. Ensure all the circuits are functioning correctly and no error codes are displayed.
  • Install the ECU: Reconnect the connectors to the ECU and plug it back into the vehicle. Reconnect the negative battery cable and turn on the ignition. Test the vehicle to make sure the ECU is functioning correctly.

Some specialized tools may be required for the job, and you should consult an automotive technician if you are unfamiliar with ECU repairs. The same goes for the replacement process. 

Reason 3: Cylinder Misfire

A misfiring cylinder can also cause code 84 to appear. Various things, such as a bad spark plug, low fuel pressure, or a vacuum leak, can cause a problem inside the vehicle. In some cases, the root cause may not be easy to determine.

A misfiring cylinder is usually connected to the speed sensor through the engine’s crankshaft position sensor (CPS). The CPS senses the speed and position of the crankshaft and sends a signal to the engine control unit (ECU).

The ECU then uses the signal to detect the misfiring cylinder so the code appears.

Symptom: Rough Idling

When a cylinder misfires, it doesn’t produce the correct amount of power, which can cause the engine to run roughly. This may be noticeable as an increase in vibration, or noise can decrease fuel economy.

Solution: Replace Spark Plug, Fuel Injector, Or Ignition Coil

The best solution may be to have the ATV taken to a mechanic for diagnosis. You may need to replace faulty components, such as the spark plug, fuel injector, or ignition coil.

You can also fix a vacuum leak by first identifying the source of the leak, for example, if there are any cracks or loose connections. Once done, the appropriate sealant or adhesive can patch the leak. Then the error codes may not appear again. 

Reason 4: Low Battery Voltage

There are a few things that can cause low battery voltage inside an ATV. A battery can become discharged if it is not used regularly or has a problem with the charging system.

If the battery is weak or has a low charge, this can impede the proper functioning of the speed sensor. The sensor needs a certain amount of electricity to measure the vehicle’s speed correctly, so the speed sensor may not be able to detect the correct speed.

When this situation arises, code 84 will flash to show you how the speed sensor is not functioning at its best. 

Symptom: Corroded Or Loosened Connections

Corroded or loose connections can cause a decrease in electrical current, which can lead to several issues, including a loss of power, fluctuations in voltage, and even a complete failure of electrical systems.

And so, necessary fixes are required. 

Solution: Secure The Battery Connection And Lubricate Or Replace It

The simple solution is three-fold and needs some attention to perform the job. Here are a few things to do:

  • To secure the configuration, tighten battery connections with a wrench or socket set. 
  • Apply a lubricant such as silicone grease or automotive cleaner sprays to the terminals and connectors. 

This will help remove any corrosion that may have built up over time. If the problem doesn’t solve, simply replace the battery. 

Reason 5: Low Fuel Levels

Some of the most common causes of low fuel levels include constantly riding at high speeds, riding in rugged terrain, and carrying too much weight.

If you have not regularly checked on the fuel pressures, lowering fuel levels can cause the code to appear. The speed sensors will react to irregular fuel pressures and stop functioning. 

Symptom: Engine Not Burning Fuel Adequately

If the fuel is dirty or has water, the engine will not burn it as effectively. Also, if the engine is not tuned correctly or has a dirty air filter, it will not burn fuel adequately.

Solution: Replace The Fuel Pump

Replacing the fuel pump is the best idea. Remove the old one and install a new fuel pump. The best way to do this is to access it from underneath the vehicle. 

First, you need to remove the four bolts to free the pump. Once it is free, disconnect the hoses and wiring that connects the pump and remove it from the vehicle.

The new pump can then be installed by reversing these steps. Be sure to reconnect the hoses and wiring properly and tighten all bolts before starting the engine.

How To Check Codes On Polaris Rangers

Polaris RZR Engine code checking

The Diagnostic Code Screen can be accessed by pressing and holding the MODE button, which will open the Options Menu. If any codes have been set during the current ignition key cycle, the option to select “Diagnostic Codes” will be available. 

Diagnostic Codes

Source: Ranger Polaris

You can cycle through the codes using the Up/Down buttons. In the Code Screen, Area A will display FMI, Area B will display SPN, and the Clock Area will display the count. To exit the Options Menu, you can select the “Exit Menu” function, press and hold the MODE button, or wait 10 seconds without pressing any button.

How Do You Reset The Engine Code On A Polaris?

RANGER 570 Battery Removal and Installation

You must remove and reconnect the battery to reset the engine code on a Polaris ATV. This can be done by disconnecting the negative and positive terminals and connecting them again after around 20 to 30 minutes.

In addition, you can find the diagnostic connector to reset the engine code on a Polaris ATV. It is usually located near the battery and will be a white four-pin connector.

Once you have found it, use a jumper wire to short the two pins together. This will also reset the engine code.

How To Prevent Polaris Ranger Code 84?

Polaris RZR Ranger Battery checking

There are a few things that you can do to help prevent code 84 from flashing on Polaris Ranger ATVs. Here are some points to consider:

  • You can ensure the battery is fully charged before starting the vehicle. 
  • You can also check the fuses and ensure they are all in good condition. If there is a problem with any of the fuses, it could cause code 84 to flash. 
  • Check the wiring harness and ensure it is all in good condition. If there is any damage to the wiring harness, it could also cause code 84 to flash.

Regularly checking these areas will prevent any of the 5 problems indicated above. This means you are ensuring that your machine is more long-lasting. 


How is the Polaris Ranger check engine light reset done?

First, find the diagnostic connector to reset the check engine light on a Polaris Ranger. And then, connect a jumper wire from pins 2 and 3 on the diagnostic connector. When done, turn on the ignition and wait for the light to reset.

Will an engine code reset itself?

Generally speaking, most engine codes will not reset themselves without physical interventions. It is good to do the work with the help of a qualified mechanic, as you may want to prevent hurting yourself or the machine while resetting the system. 

How long does it take for an engine code to go away?

Some engine codes go away right away within a few minutes. Other codes might take a while to go away, as this mainly depends on the type of code you get. For example, code 84 may go away right the moment you have fixed any of the issues. 


The bottom line is that the Polaris Ranger code 84 indicates that you are working on the refurbishment of the machine. Otherwise, there will be an impact that may cause the rider to die sooner. 

Hopefully, you will be successful with all the indications. We will go now, see you soon.


Mark Williams

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