9 Tips to prevent car theft

How to Prevent Car Theft

Antitheft systems have been required in all passenger and light truck vehicles since 1997. The early systems relied on specially coded keys and, later on, keys with Radio Frequency Identification (RFID) transponders built into the key head. More recently, carmakers have begun offering keyless push-button start systems using RFID technology built into the fob. RFID technology was originally thought to offer greater theft protection than the earlier technologies. Unfortunately, it’s just the opposite. Car thieves have figured out how to outsmart RFID fob technology using relay devices that copy and retransmit the data from your fob, allowing thieves to drive off with your vehicle. In another method, car thieves reprogram your car’s computer to accept a different key. In this article, I’ll give you a brief summary of how these theft techniques work, and then I’ll walk you through 10 ways to prevent car theft.

How car thieves steal cars using a relay system

Your key fob’s remote keyless entry feature lets you unlock your doors or open the rear hatch up to 50 feet away. However, your key fob’s secure antitheft signal only works within a few feet of the car. Car thieves defeat this feature by intercepting the antitheft signal from your key fob and relaying it to a partner standing next to your car. The accomplice uses a receiving and re-transmitting device, tricking the car into unlocking and starting as if the fob were nearby. Here’s how it works:

Scenario #1— You keep your keys near the door

The thieves first scout the neighborhood for newer cars and trucks equipped with the push-to-start feature. One thief stands next to the vehicle while the other walks up to the house and uses a scanning device to detect your fob’s signal. If it detects a signal, the thief at the house captures and re-transmits the signal to the partner in the vehicle, who then unlocks the doors, starts the car, and drives it off.

Scenario #1— They hang around in a parking lot

The scheme works the same way, where one person stands near the vehicle while the other person follows you into the store after you’ve parked your car. They use the relay devices to clone and re-transmit your fob signal and steal your car.

How car thieves steal cars using OBD reprogramming

Step 1: Set up the reprogramming device with your car’s VIN

Key reprogramming devices are commercially available for locksmiths and mechanics, but car thieves use them to steal cars. The process starts with the thieves entering and copying the VIN found under your windshield. They then set up the programming on their device so it’s ready to go the instant they gain access to your vehicle.

Step 2: Gain Physical Access to the Vehicle

In the next step, thieves access the car’s interior. Common methods include:

• Keyless Entry Relay Attacks: Using a relay device, thieves extend the signal from a key fob inside a home to unlock the car.
• Breaking In: Physically breaking a window or forcing a door open.

Step 3: Reprogram your car’s computer to accept a different fob

Your car’s OBD port is a standardized interface located under the dash. The thieves plug into it and immediately program the new key. The thief can start the car as if they had an original key. This process can take as little as a few minutes with the right tools and experience.

10 Ways to Prevent Car Theft

1) Defeat relay theft by using a Faraday Bag or Box— A Faraday bag or box is a simple and effective way to block the signal from your key fob.

Drop your keys and Fob in a faraday box and close the lid to prevent car theft

These devices are lined with materials that prevent radio frequencies from escaping, rendering relay theft attempts useless.

At home, rather than hang or drop your fob near the door, simply toss it into a Faraday box and close the lid. That’s 100% effective in defeating the relay theft system. If you’re out and about, slide your fob into a Faraday pouch.

The Samfolk Faraday box shown to the right comes with two Faraday sleeves for your fobs when you’re away from home. Buy the Samfolk Faraday box from Amazon. It comes in three sizes: Small $13, Medium #16 and Large $22

If you want just the sleeves, try this product from Amazon.

Slide your fob into a Faraday pouch to prevent car theft

The seller offers three sizes: Small 3.15″ x 4.5″, Medium 3.5″ x 5.5″, and Large 4.13″ x 8.26″

2) Use a steering wheel lock, especially if you own a high-theft vehicle— It’s not foolproof, but it does provide deterrence.

A steering wheel lock sends a visual signal to would-be car thieves that your car is going to harder to steal. In other words, it says, “If you want this car, you’re going to have to work harder for it and it’s going to take much longer than another car that doesn’t have this kind of deterrent. So choose another car.”

Aside from the well-known Hyundai and Kia thefts, other commonly stolen vehicles include: Chevrolet Silverado 1500, Honda Accord, Honda Civic, and the Ford F150 Series Pickup (According to the National Insurance Crime Bureau

Tevlaphee steering wheel lock

According to Car and Driver Magazine, the best steering wheel lock is the Tevlaphee Universal Steering Wheel Brake Lock shown to the right. It connects to the brake pedal and steering wheel. According to the product description, it’s made from aluminum alloy and steel. The seller states that it’s sturdy and durable, prevents cutting, and resists pry, saw, hammer, and Freon attacks.

Here’s what Car and Driver said about the Tevlaphee lock:

“Overall, it’s the most secure and user-friendly option we encountered. Without hesitation, the Gear Team recommends it as our best choice. How We Broke It: We didn’t! In our testing, the Telvaphee could not be broken.”

Find the Tevlaphee lock at Amazon for $44

3) Install an OBD Port Lock— Prevent key reprogramming

There are two ways to secure your OBD port: 1) Install an OBD Lock, and 2) Relocate the original OBD port and install a dummy OBD port. A good port lock costs about $100 and requires some installation. You’ll have to remove the lock cover any time your car needs service or software updating. I consider that a minor inconvenience compared to having your car stolen.

VVT OBD Lock

The VVT OBD Port Lock is made by Vargasturbo.com.  The manufacturer states they use 5 types of screw head designs for every 200 OBD-LOCKS made. So, only 40 OBD-LOCKS are using the same head design worldwide. In other words, they redesign the screw heads with every batch of 200 OBD-LOCKS.

Find the VVT OBD Lock at Amazon for $99.

Dummy OBD Port

Find the dummy port for your car on DummyOBD on eBay. The company sells dummy kits for many car brands for under $30. To install, unscrew the OBD port from its location. Connect the original port to the cable, tuck it up under the dash, and secure it with the zip ties. Then, mount the dummy OBD port in the original spot. As with the OBD port lock, you’ll have to notify the shop about this conversion if you need a service that requires access to the OBD port.

Dummy OBD port

4) Activate any additional security features in your vehicle.

Some vehicles come with built-in security options that are mostly underutilized. For instance, some key fobs allow you to disable the passive entry system, making relay theft impossible. Additionally, enabling features like a PIN-to-drive system adds an extra layer of protection. With this feature, a thief would need to know a specific PIN before the car will start.

5) Install an Aftermarket Alarm system

Yes, your car came with an anti-theft alarm. But now the thieves know how to defeat it. So adding an aftermarket alarm provides an additional layer of security.

6) Install a Dash Cam with Parking Mode

Dash cams with parking mode can record motion or impact events even when your car is turned off. While this won’t prevent theft, it can capture valuable evidence and discourage would-be thieves from targeting your vehicle.

7) Cover your VIN

Covering the VIN under your windshield won’t prevent car theft because the thieves can find your VIN on a label inside the driver’s door. But if they can’t see the VIN from the outside, they can’t program their re-keying device before breaking into your car, and that’s a deterrent. Find the plate below on Amazon for $10

blank VIN number plate

Use black electrician’s tape or a fake VIN tag to cover the VIN under your windshield.

8) Install a GPS tracking system

Explore anti-theft tracking systems like Lojak

9) Park Strategically

Where you park matters, so search for a well-lit area with high-traffic areas or secure garages. Thieves are less likely to target a car parked where they’re likely to be seen or interrupted.

NOTE: Ricksfreeautorepairadvice.com receives a commission on products purchased through the links in this article.

©, 2025 Rick Muscoplat