Mechanic Wiki: How to Delete a Lost Key from BYD Han EV Memory

Learn how to delete a lost key from BYD Han EV memory using LAUNCH X431 IMMO Elite. Step-by-step guide, prerequisites, troubleshooting, and FAQs. Secure your EV in under 5 minutes.

Published: May 26, 2026

Quick Answer: Delete a Lost Key from BYD Han EV in Under 5 Minutes

If you’ve lost a key to your BYD Han EV, you can permanently erase it from the vehicle’s memory using the LAUNCH X431 IMMO Elite. This prevents the lost key from starting the car or accessing the system. The process requires at least one working key, a fully charged 12V battery, and the latest IMMO software. After deletion, the lost key is disabled and cannot be reused on that vehicle.

Understanding the BYD Han EV Immobilizer System

Modern electric vehicles like the BYD Han EV use a Passive Entry Passive Start (PEPS) system. This means the car detects the key fob’s RFID chip when you approach or press the start button. The system stores the unique IDs of all registered keys in the ECU (Electronic Control Unit). When a key is lost, that ID becomes a security risk — anyone finding the key could potentially start your car.

Deleting a lost key from BYD Han EV memory removes that ID from the ECU’s authorized list. The key becomes useless for that vehicle, even if the battery is replaced. It’s a critical step after losing a key, especially if you suspect theft or misplacement.

Why Use the LAUNCH X431 IMMO Elite for This Job?

The LAUNCH X431 IMMO Elite is a professional-grade immobilizer tool designed for key programming, PIN reading, and key deletion across over 120 car brands. For the BYD Han EV specifically, it offers:

Direct access to the PEPS module without needing dealer-level passwords
Automatic VIN recognition for 2020–2024 models
Online PIN retrieval when the factory PIN is not available
Step-by-step key deletion that follows OEM procedures

Many generic OBD scanners can read fault codes but cannot touch the immobilizer system. The IMMO Elite is purpose-built for this work. I’ve used it on multiple BYD models, and it reliably handles the security gateway handshake that trips up cheaper tools.

Prerequisites Before You Start

Before you attempt to delete a lost key from BYD Han EV memory, gather the following:

LAUNCH X431 IMMO Elite tablet, main unit, and OBD II cable
Latest software — go to the app store on the tablet and install all updates for the “X431 IMMO” application
At least one working key — the procedure cannot proceed without a valid key to authenticate
Fully charged 12V auxiliary battery — a low battery is the #1 cause of failed key programming
Stable internet connection (Wi-Fi or hotspot) — for online PIN services if needed

Critical Safety Checks

Charge the 12V battery: Electric cars have sensitive electronics. If voltage drops below 12V during programming, the ECU may lock up. If in doubt, connect a battery maintainer.
Turn ignition ON: Press the start button once without touching the brake pedal. The dashboard should light up, and the “READY” light should come on (or the instrument cluster should show power).
Put the vehicle in Park: Make sure the gear selector is in Park and the parking brake is engaged.
Work in a stable environment: Avoid areas with strong electromagnetic fields (e.g., near large transformers or radio towers). They can interfere with the tool’s communication.

Step-by-Step: Delete a Lost Key from BYD Han EV Memory

Follow these steps exactly. Skipping or rushing any step can cause errors.

Step 1: Connect and Power the LAUNCH X431

Plug the main unit into the tablet using the USB cable.
Insert the OBD II connector into the vehicle’s diagnostic port (located under the driver’s side dashboard, near the hood release).
Turn the ignition ON (press start button once, no brake).
On the tablet, tap the “DC In” icon at the top of the screen to establish communication.
Wait for the tool to display the vehicle’s 12V battery voltage. It should read above 12.0V.

Step 2: Launch the IMMO Elite Application

From the home screen, tap “X431 IMMO”.
Select “IMMO Elite” from the menu.
The tool will attempt to read the VIN automatically. If it succeeds, confirm the vehicle identification (BYD > Han > EV).
If VIN auto-detect fails, manually navigate: BYD > Han > EV (2020–2024). Choose the correct year range for your car.

Step 3: Enter the Immobilizer System

After vehicle selection, tap “Immobilizer”.
The tool will load the PEPS system information. Look for a menu entry called “Immobilizer / Smart Key System” or “PEPS”.
The system will now ask for a Security PIN Code. This is a four-to-six-digit number required to access key programming.
- Option A – Auto Read: Tap “Read PIN”. The tool will try to calculate the PIN from the ECU. This works on many BYD models.
- Option B – Online: If auto read fails, tap “Online PIN”. You’ll need an active internet connection and possibly credits in your LAUNCH account. The tool will retrieve the PIN from a remote server.
- Option C – Manual Entry: If you already know the PIN (e.g., from a sticker on the ECU or previous service), enter it directly.

Once authenticated, you’re inside the immobilizer system.

Step 4: Navigate to Key Programming

From the main IMMO menu, select “Key Programming”.
Look for “Key Delete” or “Delete Lost Key”. Some software versions label it “Erase Key”.
Important: Some firmware versions require you to perform a “Key Learning” (add all valid keys) before allowing deletion. If prompted, follow the on-screen instructions to learn your working keys first.

Step 5: Execute the Deletion

The screen will display a list of known keys, usually labeled “Key 1”, “Key 2”, etc., along with their status (e.g., “Programmed” or “Unknown”).
Select the slot that corresponds to the lost key. If you’re unsure which slot is the lost key, check the description (some tools show the key’s serial number or last used date).
Tap “Delete”.
The tool will now give on-screen prompts. Typically, you will be asked to:
- Turn the ignition OFF (press the start button to turn off the dash).
- Wait 10 seconds.
- Turn the ignition ON again.
- Press the start button with the valid working key inside the car (usually on the reading coil near the start button).
After the cycle, the tool will display: “Key Deleted Successfully”.

If the deletion is confirmed, exit back to the main menu.

Step 6: Verify the Result

Turn the ignition OFF and remove the OBD connector.
Start the vehicle with the working key — it should start normally.
If you have the lost key in hand, try to start the car with it. The instrument cluster should show a message like “Key Not Detected” or “No Key”. The car will not start.
Also test remote lock/unlock functions on the working key to ensure they still work (they should, as those are handled by a separate module).

Troubleshooting Common Problems

Even with the right tool, things can go wrong. Here are the most frequent issues and how to fix them.

Problem 1: Tool Cannot Read the VIN

Cause: Poor OBD connection or outdated software.

Solution: Unplug and replug the OBD cable. Make sure the ignition is ON. Check for Wi-Fi and update the X431 IMMO app via the tablet’s app store. If still no VIN, manually select BYD > Han > EV.

Problem 2: “Key Deletion Failed” Error

Cause: Low battery voltage, corrupted PIN, or a glitchy ECU.

Solution:

Charge the 12V battery overnight or connect a charger.
Disconnect the negative terminal of the 12V battery for 60 seconds, then reconnect. This resets the immobilizer ECU.
Perform a full “Key Learning” first: add all working keys to the system, then try deletion again.
If the error persists, try a different ignition cycle (OFF, wait 20 seconds, ON).

Problem 3: Lost Key Still Starts the Car

Cause: The deletion did not save correctly, or you selected the wrong key slot.

Solution: Repeat the process exactly. Pay close attention to the “Turn OFF / Wait 10s / Turn ON” sequence — timing matters. If it still fails, the ECU may have a firmware issue or the tool’s software is not fully compatible with that specific model year. Contact LAUNCH support for a software patch.

Deeper Dive: What This Means for Your EV

How EV Immobilizers Are Different

Electric vehicles are more sensitive to voltage drops during programming than gas cars. The high-voltage traction battery is isolated, but the 12V auxiliary battery powers the ECU and the tool. A weak battery can interrupt the flash process, potentially bricking the PEPS module.

Additionally, many modern EVs (including BYD) use secure gateways that encrypt communication between the OBD port and critical modules. That’s why cheap tools fail — they can’t authenticate past the gateway. The LAUNCH X431 IMMO Elite is certified to work with these security protocols.

Risks of Using Unsupported Tools

Using a generic OBD scanner to attempt key deletion can:

Corrupt the PEPS module — you may need to replace the entire module, costing hundreds.
Trigger a security lockout — the car may refuse all keys, requiring a tow to the dealer.
Void your warranty — unauthorized programming attempts can be logged by BYD’s diagnostic systems.

Stick with professional-grade tools like the IMMO Elite, or visit a trained technician.

Frequently Asked Questions

Does deleting a lost key affect my memory seats or remote start?

No. Deletion only removes the RFID chip authorization from the immobilizer system. Your seat memory, remote start, and keyless entry are managed by the Body Control Module (BCM) and remain unchanged. Those features are tied to the key’s hardware ID, not the immobilizer database.

Can I delete a key without having any working key?

No. You must have at least one valid working key to authenticate yourself to the immobilizer system. Without it, the tool cannot access the programming functions. If you’ve lost all keys, you’ll need a dealer or a specialist who can read the ECU directly and write a new key.

Will this void my BYD warranty?

Potentially, if damage occurs. BYD may deny a warranty claim on the PEPS module if they detect unauthorized programming. The LAUNCH X431 is a reputable tool, but use it at your own risk. For vehicles still under factory warranty, we recommend using a BYD dealership for key deletion.

How long does the whole process take?

Typically 15 to 30 minutes, including connecting the tool, reading the PIN, performing the deletion, and testing. Most of the time is spent waiting for the tool to communicate with the vehicle.

Can I reuse the deleted key later on the same car?

No. Once a key is deleted from the BYD Han EV memory, it is permanently unpaired. The only way to use it again is to reprogram it to a different BYD vehicle (if compatible), and only if that vehicle is put into key learning mode.

Does this work for all BYD Han EV years (2020–2024)?

Yes, the LAUNCH X431 IMMO Elite supports the vast majority of BYD Han EV models, including facelift versions. However, always update your software to the latest version for the best compatibility. Some 2024 vehicles with new ECU hardware may require a software patch — check LAUNCH’s support site before starting.

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 delivering reliable technical expertise and practical training solutions.

For inquiries and equipment purchases, please visit https://carlifterph.com/

For more information on setting up your LAUNCH X431, see our guide on LAUNCH X431 initial configuration and updates. If you need help with other BYD key programming tasks, check out our article on BYD Han EV key learning procedure.

How to Delete a Lost Key from BYD Han EV Memory | LAUNCH X431 Guide