How to Test and Replace Lexus RX 350 Key Fob Battery: A Complete Guide

Ever found yourself stuck with a dead car key battery at the worst possible moment? Frustrating, right? Well, you’re not alone. Many Lexus RX 350 owners face this issue, but fret not, because we’ve got your back! In this article, we’ll walk you through the simple steps to change the car key battery in your Lexus RX 350.

Imagine being able to swiftly replace your car key battery without any hassle. No more panicking when your key fob starts acting up or failing to unlock your car. By learning this quick and easy process, you’ll save yourself time, money, and the stress of dealing with a malfunctioning key fob.

Get ready to empower yourself with the knowledge and skills to tackle this common car key issue like a pro. Say goodbye to those inconvenient moments and hello to a smoothly functioning car key – all thanks to the simple steps you’re about to discover.

Step 1: Gather the necessary tools

When changing the car key battery in your Lexus RX 350, it’s essential to have the right tools at your disposal. Here’s what you’ll need:

  • New CR2032 battery
  • Flathead screwdriver or coin
  • Small precision Phillips head screwdriver

Having these tools ready will make the process of replacing your car key battery much smoother and hassle-free.

Step 2: Locate the key fob slot

When changing the key fob battery in your Lexus RX 350, it’s essential to locate the key fob slot accurately. This slot can usually be found on the side or at the back of the key fob. It’s a small indentation where you can insert a tool to open the casing.

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Here are the key steps to locate the key fob slot in your Lexus RX 350:

  • Identify the key fob: The key fob is the device you use to lock, unlock, and start your vehicle remotely. It typically has buttons and a small Lexus logo on it.
  • Check the key fob: Look closely at your key fob to locate any visible slots or indentations. These are usually designed to help you open the fob to access the battery compartment.
  • Inspect all sides: Carefully examine all sides of the key fob, including the top, bottom, and edges, to ensure you don’t miss the slot where the key fob can be opened.

Locating the key fob slot correctly is crucial for the smooth replacement of the car key battery in your Lexus RX 350. By following these steps, you’ll be well on your way to completing this task successfully.

Step 3: Open the key fob

To access the battery, you’ll need to open the key fob. Here’s how you can do it:

  • Locate the Seam: Examine the key fob to identify the seam where the two halves of the key fob meet.
  • Use a Pry Tool: Insert a flathead screwdriver or a coin into the seam and gently twist to pop open the key fob. Be careful not to apply too much pressure to avoid damaging the fob.
  • Separate the Halves: Once the key fob is partially open, carefully separate the two halves to reveal the battery compartment inside.
  • Mind the Buttons: Pay attention to any buttons or components that may come loose as you open the key fob. Keep them organized to easily put everything back together later.
  • Inspect the Interior: Take a quick look inside the key fob to familiarize yourself with the layout. This will help when it’s time to replace the battery.

Remember that each key fob may have a slightly different opening mechanism, so be sure to proceed with caution and refer to your car’s manual if needed.

Important Data
Always handle the key fob with care to prevent any damage.
Opening the key fob gently is crucial to avoid breaking it.

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Step 4: Remove the old battery

To continue with the battery replacement process in your Lexus RX 350, it’s time to remove the old battery. Here’s how:

  • Locate the old battery in the fob. It’s usually a small, circular object.
  • Carefully remove the old battery. You may need a small tool like a flathead screwdriver to help with this step.
  • Pay attention to the orientation of the battery as you take it out. Note which side is facing up.
  • Dispose of the old battery properly. It’s important to recycle it in accordance with local regulations.
  • Avoid touching the new battery with your fingers. Oils from your skin can affect its performance.
  • Prepare to insert the new battery once you’ve safely removed the old one.

This process sets the stage for installing the new battery correctly, ensuring your key fob continues to work effectively.

Step 5: Insert the new battery

Let’s insert the new battery into your Lexus RX 350 key fob to ensure smooth operation. Here’s what you need to do:

  • Handle the new battery carefully to avoid any damage.
  • Position the battery correctly in the designated slot to match the orientation of the old one.
  • Slide the battery into place securely, making sure it fits snugly.
  • Avoid touching the battery with your bare hands to maintain its performance.
  • Test the key fob to confirm that the new battery is functioning correctly.
Important Information Details
Handling the new battery Careful handling is crucial
Positioning the battery Match the orientation
Securing the battery Ensure a snug fit
Testing the key fob Confirm proper functionality

Step 6: Close the key fob

To complete the battery replacement process, it’s time to close up the key fob. Here’s how you do it:

  • Align the cover: Match up the back cover with the key fob body. Be sure it’s properly aligned before you click it back in place.
  • Press firmly: Apply even pressure to the cover. You should hear a series of clicks as it snaps back together securely.
  • Confirm closure: Give the key fob a gentle squeeze to ensure it’s tightly shut and there are no gaps around the edges.
  • Test the buttons: Before you consider the task complete, test all the buttons on your key fob to make sure they work properly.

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Key Information
Alignment: Match cover with key fob body.
Pressure: Firmly press cover until it clicks.
Closure: Ensure key fob is securely shut.
Testing: Verify all buttons function correctly.

Step 7: Test the key fob

Once you’ve replaced the battery in your Lexus RX 350 key fob, it’s crucial to test it to ensure everything is working as it should. Here’s how you can do it:

  • Press each button on the key fob to check if they respond.
  • Make sure the buttons feel clicky and responsive when you press them.
  • Test the range by using the key fob from different distances.
  • If any button is unresponsive, you may need to repeat the battery replacement process or seek professional help.

Remember, testing the key fob will give you peace of mind that your battery replacement was successful and that your key fob is fully functional.


That’s it! Remember to test your key fob thoroughly after changing the battery. Press each button, check for responsiveness, test the range, and address any issues promptly. Testing ensures your key fob works perfectly. Enjoy the convenience of your fully functional Lexus RX 350 key fob!

Frequently Asked Questions

How should I test the key fob of a Lexus RX 350 after replacing the battery?

After replacing the battery, test each button for responsiveness. Check for a clicky feel, test the range from various distances, and address unresponsive buttons promptly. If issues persist, repeat the battery replacement process or seek professional help.

Why is testing the key fob important after replacing the battery?

Testing ensures the success of the battery replacement and guarantees the key fob’s proper functioning. It helps identify any issues early on and allows for prompt resolution to maintain full key fob functionality.

Battery industry professional with 5+ years of experience. Bachelor of Science in Electrical Engineering from Georgia Tech. Specializes in power systems and renewable energy.

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