Replace BYD Song Plus EV Immobilizer Module with LAUNCH X431 IMMO Elite

Published: May 26, 2026

Quick Answer: Replacing the Immobilizer Module on a BYD Song Plus EV

To replace the immobilizer module on a BYD Song Plus EV using a LAUNCH X431 IMMO Elite, you must first physically swap the module (located behind the glovebox or under the steering column), then use the X431 to learn your transponder keys, and finally synchronize the new module with the vehicle's ECU. The entire job takes 30–60 minutes. Critical warning: always back up your existing key data before disconnecting the 12V battery – a full loss of keys without a backup can lock you out permanently.

Understanding the BYD Song Plus EV Immobilizer System

What the Immobilizer Module Does

The immobilizer module is the brain behind your car's anti-theft system. It performs three essential functions:

• Prevents unauthorized engine starts – Without the correct transponder key placed near the start button, the module tells the ECU to cut fuel and ignition.
• Communicates with the key fob and ECU – It uses a 125 kHz radio frequency link to read the unique chip inside your key fob, then sends an encrypted challenge-response handshake to the vehicle's computers.
• Stores encrypted key data – The module can hold up to 4–8 keys depending on the specific BYD Song Plus EV variant. Each key’s unique ID is stored in non-volatile memory.

I’ve seen many cases where a water-damaged module loses this memory entirely, leaving the car completely dead – no crank, no start, not even an accessory power.

When Replacement Is Necessary

You should consider replacing the immobilizer module under these scenarios:

• Physical damage – Water ingress from a leaky windshield or AC drain, corrosion on the circuit board, or impact damage from a collision.
• Internal electronic failure – The module stops communicating with the LAUNCH X431 or shows a "No Response" error even with good power and ground.
• Lost all keys – If you have zero transponder keys left, the old module cannot be reprogrammed. You’ll need a new virgin module and fresh keys cut and programmed.
• Intermittent starting issues – Sometimes the module fails partially, causing the car to start only after several attempts. A scan tool can confirm immobilizer-related DTCs like P0513 or U0180.

Tools & Parts Required

Before you start, gather these items:

Pro tip: Always use an OEM module from a BYD dealer or verified supplier. Aftermarket modules often fail to match the encrypted handshake protocol, and the X431 will reject them during programming.

Step-by-Step Replacement Guide

1. Preparation & Safety

Step 1: Disconnect the 12V auxiliary battery negative terminal. On the BYD Song Plus EV, this battery is located in the front trunk (frunk) under a plastic cover. Use a 10mm wrench.

Step 2: Wait at least 5 minutes for residual voltage to drain from the vehicle's capacitors. This prevents airbag accidental deployment and protects the sensitive electronics in the immobilizer module.

Step 3: Locate the immobilizer module. On most BYD Song Plus EV models, it sits behind the glovebox or under the steering column cover, attached to a metal bracket. I’ve found it easiest to first remove the glovebox (four screws) and then look toward the passenger footwell side.

2. Removing the Old Immobilizer Module

Step 1: Use a trim removal tool to gently pry off the plastic panel covering the module area. Work around the edges – do not yank. The clips can break.

Step 2: Locate the wiring harness connector. Press the locking tab (usually a small white or blue lever) and carefully pull the connector straight out. Do not twist or force it – the pins are fragile.

Step 3: Using a Torx T20 screwdriver, remove the 2–4 screws holding the module. Keep them in a magnetic tray to avoid losing them inside the dashboard.

Step 4: Gently slide the module out. Do not touch the RF antenna (the small coil on the back) with bare fingers. Oils from your skin can detune the 125 kHz signal.

3. Installing the New Module

Step 1: Hold the new OEM module in the same orientation as the old one. The antenna coil should face the same direction (toward the driver or passenger, depending on the OEM layout).

Step 2: Tighten the Torx screws to 2–3 Nm – basically hand-tight plus a quarter turn. Over-tightening can crack the plastic housing.

Step 3: Reconnect the wiring harness. Push until you hear a distinct click. Give it a gentle tug to confirm the lock is engaged.

Step 4: Reinstall the trim panels loosely – leave them finger-tight. You’ll need to remove them again if programming fails and you have to check connections.

4. Connecting the LAUNCH X431 IMMO Elite

Step 1: Power on the X431 and ensure it has a stable Wi-Fi or cellular connection. Software updates are critical for new BYD models – I always check for updates before starting.

Step 2: Plug the X431’s OBD-II cable into the vehicle’s diagnostic port (located under the dashboard on the driver’s side, near the fuse box).

Step 3: On the X431 home screen, tap Diagnostics → BYD → Song Plus EV → Immobilizer. The tool will read the vehicle’s VIN and list the module type.

Step 4: Follow the on-screen prompts. Select Immobilizer Learning → Replace ECU/Module. The X431 will ask you to confirm that the new module is installed.

5. Programming the New Module

Step 1: The tool will prompt you for the vehicle’s security code (also called PIN or security access code). This is a 16–20 digit alphanumeric string unique to your VIN. You can obtain it from:

• A BYD dealership (requires proof of ownership and ID)
• Online VIN-based PIN services (cost $15–$30, but verify the site is reputable)
• Some LAUNCH X431 subscriptions include free PIN retrieval – check under Online Security Access.

Step 2: Enter the PIN carefully using the on-screen keyboard. If you enter the wrong PIN three times, many X431 versions will lock the immobilizer function for 24 hours. I always double-check the PIN against the VIN before typing.

Step 3: Once the PIN is accepted, select Key Learning. The X431 will instruct you to place the first transponder key near the start button (the EV start button, not an ignition cylinder).

Step 4: Hold the key fob against the start button (or the marked area on the console, depending on the model year). The X431 will read the key chip and ask if you want to add more keys. Repeat for up to 4 keys.

Step 5: After all keys are learned, the tool will display a success message. Turn the ignition off, wait 10 seconds, then turn it back on with each key to confirm the immobilizer recognizes it.

6. Synchronizing with ECU

Step 1: Some BYD Song Plus EV models require an additional ECU synchronization step. Go to the X431 menu: System Selection → ECU Programming → Sync Immobilizer.

Step 2: The tool will communicate with the ECU and exchange the encryption codes. This usually takes 2–3 minutes.

Step 3: Wait for the message "Synchronization Successful". If you see "Failed," double-check the module part number compatibility. I once spent an hour troubleshooting only to discover I had a module from a BYD Yuan Plus, not a Song Plus.

7. Final Testing & Verification

Step 1: Reconnect the 12V battery negative terminal. Torque the nut to 8–10 Nm.

Step 2: Press the brake pedal and push the start button. The car should enter READY mode (the green "READY" light on the dashboard). If it doesn’t, re-check the immobilizer communication.

Step 3: Test remote lock/unlock on each key fob. Ensure the doors respond immediately.

Step 4: Take a short test drive (at least 1 km) to allow the module to fully register with the ECU. Some BYD models will cut power after 20 meters if the sync isn’t complete.

Step 5: Only after successful testing should you fully secure all trim panels. Reinstall screws and snap clips back in place.

Troubleshooting Common Issues

"No Communication with Immobilizer Module"

• Check the OBD-II connection – Use only the X431’s included cable. Cheap extension cables can introduce noise.
• Verify battery voltage – The 12V battery must be above 12.4V. A weak battery often causes communication drops during programming. Charge it if needed.
• Force a software update – On the X431, go to Update Center and search for BYD IMMO firmware. Outdated firmware won’t recognize newer Song Plus modules.

"Key Learning Failed – Wrong PIN"

• Double-check the PIN against your dealer receipt or VIN lookup. Online services sometimes provide incorrect codes for Chinese EVs.
• Try manual entry – Some X431 versions auto-fill the PIN from a database, but that database may be wrong. Manually type it using the on-screen keyboard.
• Reset the tool – Exit the immobilizer menu completely, turn the ignition off, wait 30 seconds, then re-enter. This clears any temporary lockout counter.

"Module Not Recognized After Replacement"

• Part number mismatch – Verify that the new module’s part number matches the BYD Song Plus EV requirement. Some modules (like the T-box integrated type) look identical but have different firmware.
• Perform module virginization – If the new module was previously used in another car, it still has the old encryption keys. Use the X431’s Immobilizer → Module Virginization function to reset it to factory state.
• Reflash module firmware – Under ECU Programming, select Update Firmware. This requires internet access and a LAUNCH subscription.

"Error: Security Access Denied"

• Region lock – Some modules from non-Asian market BYDs (e.g., European spec) are region-locked and require dealer-level permissions.
• Use X431's Online Security Access – This feature connects to LAUNCH’s server to bypass regional locks. It may require a paid subscription token.
• Remote technician assistance – The X431 IMMO Elite supports remote control. You can invite a specialist to take over the tool and perform the unlock.

Topical Depth – Related Considerations

Differences Between BYD Song Plus EV and Other BYD Models

• Separate module – Unlike the BYD Atto 3 (which integrates the immobilizer into the BCM), the Song Plus EV uses a standalone module. This makes replacement simpler but the module itself is more exposed to dashboard moisture.
• RFID frequency – The key transponder runs at 125 kHz. Older BYD models (e.g., Tang before 2020) used 433 MHz. The Song Plus EV keys are not interchangeable with them.
• Immobilizer chip location – On the Song Plus key fob, the transponder chip is soldered directly to the circuit board, not removable. If the fob is damaged, you need a new key assembly (cutting the physical key blade separately).

When You Need Professional Assistance

• Lost all keys – Without a single working key, you cannot start the car even to move it. A dealer will need to virginize the new module and cut/program fresh keys. This can cost $400–$800.
• PIN retrieval locked out – If the X431 locks out due to too many wrong PIN attempts, only a dealer with direct access to BYD’s server can reset the lock counter.
• Crash damage – If the module was physically crushed in a collision, check the BMS and airbag modules too. They often share a communication bus with the immobilizer.

Preventative Maintenance

• Keep key fobs dry – Moisture corrodes the circuit board and damages the transponder chip. Replace the fob battery (CR2032) annually to maintain a strong signal.
• Avoid aftermarket start buttons – Cheap push-start button covers can block the RF field of the immobilizer antenna, causing intermittent "Key Not Detected" errors.
• Update your X431 regularly – BYD releases new firmware for the immobilizer protocol roughly every 6 months. Staying current prevents future communication failures.

Frequently Asked Questions (FAQ)

Can I replace the immobilizer module without LAUNCH X431?

No. The BYD Song Plus EV uses a proprietary encrypted handshake that only specialized diagnostic tools like the LAUNCH X431 IMMO Elite can perform. Generic OBD-II scanners cannot read or write to the immobilizer module.

How much does it cost to replace the immobilizer module?

If you do it yourself, expect $80–$150 for the module plus the cost of owning or renting an X431 ($300–$600). At a dealership, total cost including parts and programming ranges from $400 to $800.

Will replacing the immobilizer module void my warranty?

Performing the replacement yourself may void the electrical warranty on the affected circuit. However, using OEM parts and following the correct procedure minimizes risk. If you are still under factory warranty, consider having a dealer do the work.

How do I get the security PIN for my BYD Song Plus EV?

You can obtain the PIN from a BYD dealer (bring your ID and proof of ownership) or from a reputable online VIN-based PIN service for $15–$30. Some LAUNCH X431 subscriptions include no-cost PIN retrieval – check under "Online Services" on the tool.

What happens if I install a used immobilizer module?

A used module retains the encryption keys from its previous vehicle. It must be virginized (reset to factory default) before it can be programmed to your Song Plus EV. The LAUNCH X431 IMMO Elite includes a virginization function for most BYD modules. Without it, the used module will refuse to learn your keys.

Can I use the LAUNCH X431 IMMO Elite for other car brands?

Absolutely. The X431 IMMO Elite covers a vast range of manufacturers including GM, Ford, Toyota, VW, BMW, and many others. Its BYD coverage is one of the most comprehensive on the market, but always verify you have the latest software before starting any job.

About the Author: Erwin Salarda is an Automotive Service Equipment Technician based in the Philippines, specializing in computerized automotive diagnostic equipment such as OBD scanners and wheel alignment systems. Since 2012, he has been actively providing technical support, equipment installation, troubleshooting, after-sales service, and hands-on training for automotive service equipment used by workshops and automotive professionals.

He has received specialized training from international suppliers and manufacturers, including Launch X431 in Shenzhen, China, Lawrence Engineering Company in Guangzhou, China, and 3Excel Wheel Alignment Company in Shenzhen, China. Through these trainings, he developed advanced expertise in automotive diagnostics, calibration, wheel alignment systems, and computerized automotive service technologies.

Erwin Salarda provides professional after-sales support and technical training for automotive diagnostic and wheel alignment equipment, helping clients maximize the performance and proper use of their tools and systems. His experience covers equipment setup, software updates, calibration procedures, troubleshooting, and operational guidance for automotive workshops and service centers.

With more than a decade of experience in the automotive equipment industry, Erwin Salarda continues to support automotive businesses by

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