Step-by-step guide to recover a BYD Seal with all keys lost using the LAUNCH X431 Key Programmer. Learn the IMMO procedure, PIN code requirements, and troubleshooting tips.

How to Use LAUNCH X431 Key Programmer to Recover from BYD Seal All Keys Lost Scenario

Published: May 26, 2026

Quick Answer: The Smart Key Recovery Path for BYD Seal

The situation: You have zero working keys. The BYD Seal won’t detect any smart key, you can’t unlock the doors, and the immobilizer prevents the car from starting.

The solution: You need a professional-grade diagnostic tool with immobilizer and key programming capabilities — specifically the LAUNCH X431 Key Programmer (models like X431 PAD VII or X431 IMMO Elite). The three-step recovery process is: (1) establish OBD-II communication, (2) perform the "All Keys Lost" procedure in the IMMO menu, and (3) program a new blank smart key fob. Success depends on having a valid PIN code for the vehicle.

Understanding the "All Keys Lost" Nightmare

Before diving into the procedure, it’s important to understand why this is a high-stakes scenario for a modern EV like the BYD Seal. Unlike older cars where a $20 key cutter could get you moving, the Seal uses a rolling-code encryption system tied to a dedicated immobilizer module inside the Body Control Module (BCM).

What Happens When You Lose All BYD Seal Keys?

Physical lockout: You cannot unlock the doors. Most BYD Seal fobs include a hidden mechanical key blade — if you have that, you can manually open the driver’s door. Without it, you’ll need a professional locksmith to gain entry without damaging the vehicle.
Immobilizer engaged: The ECU and BCM will not authorize a start. Pressing the start button does nothing.
No push-to-start: The car doesn’t recognize any key fob signal. Even if you hold a new blank fob near the start button, nothing happens until the BCM learns it.

Why You Can't Use a $50 Programmer

Cheap OBD tools cannot communicate with the BYD Seal's secure gateway. The LAUNCH X431 is required because it has manufacturer-level license packages — specifically the IMMO Plus or Diag 4.0 software add-ons. These packages give the tool access to the encrypted immobilizer system, allowing it to erase lost keys and write new ones.

Prerequisites: What You Need Before Starting

Before you even touch the car, gather everything you’ll need. Running out mid-procedure can brick the process.

Hardware Requirements

LAUNCH X431 tool: The PAD VII or X431 IMMO Elite models are recommended. The X431 V+ may work with an additional IMMO license, but the dedicated IMMO Elite is the most reliable choice.
Stable vehicle power: The BYD Seal’s 12V auxiliary battery is small. Key programming drains it fast. Connect a battery maintainer (set to 12V, 2–10 amps) to the auxiliary battery terminals under the hood. Never rely on the main EV battery alone — the 12V system powers the BCM during programming.
Blank smart key fob: Must match the correct frequency for your region. BYD Seal typically uses 433 MHz for North America and 2647 MHz for Europe and Asia. Aftermarket fobs sometimes fail; use an OEM BYD fob or a high-quality compatible blank from brands like JMD or ORIGO.
OBD-II cable: The standard 16-pin cable that comes with the X431.

Software & Data Requirements

Latest X431 software: Update the “BYD” and “IMMO” packages via Wi-Fi before starting. An outdated software version often causes “Can’t Find IMMO Menu” errors.
PIN code: This 4- to 8-digit security code is unique to your vehicle’s VIN. You cannot program keys without it.
Internet connection: The X431 needs online access to download data, verify licenses, and complete authorization steps.

Step-by-Step: Recovering the BYD Seal from All Keys Lost

Follow these steps precisely. Skipping a step or rushing through can cause lockouts and wasted time.

1. Gain Physical Access to the OBD Port

The car is locked. How do you get inside?

Option A: Use the mechanical key blade hidden inside the key fob (if you still have the fob body). Insert it into the driver’s door lock cylinder and turn.
Option B: If no key blade exists, call a professional automotive locksmith. They can pick the lock or use an air wedge and rod to pop the door handle and unlock it without damage.

Once inside, locate the OBD-II port under the driver’s side dashboard, near the footwell. It’s a standard 16-pin connector.

2. Connect the LAUNCH X431

Turn the ignition OFF.
Plug the X431 main cable into the OBD-II port.
Press the start button once (without your foot on the brake) to turn the ignition ON.
The X431 powers up and prompts you to select the vehicle.

3. Select the Correct Vehicle Profile

Navigate through the X431 menu:

Diagnosis > BYD > Seal (choose the model year range: 2022–2024).
The software automatically detects the VIN. Confirm it matches the vehicle’s VIN on the dashboard or door jamb.

4. Enter the Immobilizer (IMMO) System

From the diagnostic menu, go to:

Special Functions > IMMO / Key Programming

The tool will ask: “Are all keys lost?” Select YES. This tells the system to bypass the “add key” procedure and instead erase all existing key data.

5. Input the Security Code

The X431 displays a field for the PIN code. Type in the code you obtained from your provider (e.g., AutoAuth, CarRepair.ca).

Important: The system typically allows three attempts. After three wrong entries, the BCM locks you out for 30 to 60 minutes. Double-check the code before entering it.
If you don’t have the code yet, stop here and contact a provider. Do not guess.

6. Erase Lost Keys

Select Erase All Keys from the IMMO menu. Confirm the action when prompted. This removes all previously stored key data from the BCM memory. The car now has zero recognized keys — but that’s exactly what we want before programming a new one.

7. Program the New Key

Hold the new, blank key fob near the start button (or near the center console, as shown on the X431 screen). Some models require the fob to be placed in a specific spot — follow the on-screen instructions.
Select Program New Key.
The X431 writes the key data to the BCM. This takes about 30 seconds.
Success signal: The hazard lights flash once, and the instrument cluster displays “Key Learned” or similar confirmation.

8. Final Verification and Testing

Disconnect the X431 from the OBD port.
Do not start the car yet. Wait at least 30 seconds for the BCM to complete its power cycle.
Press the start button with your foot on the brake. The car should detect the key and allow the electric motor to engage.
Test all remote functions: lock, unlock, trunk release, and panic button.
If everything works, turn off the car and test again.

Detailed Troubleshooting: Common Errors & Fixes

Error	Cause	Solution
“Communication Error”	Poor OBD connection or vehicle gateway interruption.	Reboot the X431. Check that all 16 pins are making contact. Clear any DTCs (Diagnostic Trouble Codes) from the ECU first, as some codes block IMMO communication.
“Incorrect PIN Code”	Invalid or expired security code.	Double-check the code with your provider. Try a different provider if needed. Wait 30 minutes if the BCM locked you out after three attempts.
“Blank Key Not Recognized”	Wrong frequency or incompatible aftermarket fob.	Verify the fob frequency matches your region. Use a genuine BYD OEM fob if possible. Some X431 models support only certain brands of blanks.
“Programming Failed”	Low 12V battery voltage.	Charge the 12V auxiliary battery to at least 12.5V using a maintainer. The BCM is sensitive to voltage drops during key writing.
“Can’t Find IMMO Menu”	Software not updated or insufficient license.	Update the BYD and IMMO software packages. Check that your X431 has the required IMMO license — some models need an additional subscription.

Pro Tips for Success

Use a battery maintainer. I cannot stress this enough. The 12V auxiliary battery in the BYD Seal is small — about 12Ah — and the BCM draws significant current during programming. A voltage drop mid-write can corrupt the process and require a full BCM replacement. Connect the maintainer before you start.

Program two keys. If you only have one blank fob, program it now. Then immediately go back into the IMMO menu and use the Add Key function to program a second one. Losing this single key again will require the same time-consuming procedure.

Store your PIN code safely. Save it in a password manager or a secure note. Never rely on memory. Many locksmiths and owners have been stranded because they forgot their code.

Verify tool compatibility. Not all LAUNCH X431 models come with full IMMO support. The X431 IMMO Elite and PAD VII are the safest bets. If you own an X431 V+ or earlier model, check with LAUNCH support that your unit has the correct licenses. The topic of tool compatibility is something we cover in depth in our comparison guide [link to related guide on choosing the right diagnostic tool for immobilizer work].

Frequently Asked Questions (FAQ)

Q: Can I use a cheaper tool like Autel or Topdon for this?

Possibly. Autel’s MaxiIM series (e.g., IM508, IM608) also supports BYD immobilizer functions. However, the LAUNCH X431 is one of the few tools with a dedicated, deep-specialized BYD module that covers the Seal’s unique communication protocols. For Chinese EVs, the LAUNCH X431 often has better coverage. If you already own an Autel, it may work, but the X431 is the most reliable choice for this specific scenario.

Q: Do I need a subscription for the BYD software?

Yes. The basic diagnostic subscription does not include IMMO key programming. You need either the IMMO Plus or Diag 4.0 software package. These are sold as yearly licenses, typically costing between $199 and $499 per year. Some X431 models bundle one year of IMMO access with the hardware purchase. Check your tool’s included licenses before buying.

Q: How long does the entire process take?

If you have the correct PIN code and a stable connection, the actual programming takes 5 to 10 minutes. However, gaining entry to the car, preparing the battery, obtaining the PIN code, and setting up the tool can take 1 to 3 hours your first time. Plan accordingly.

Q: What if I can’t find the PIN code online?

You have two options:

Dealership: Contact a BYD dealer, provide your VIN and proof of ownership, and request the immobilizer security code. They may charge a fee (typically $50–$150).
Online service: Use a trusted third-party provider like CarRepair.ca, AutoAuth, or KeyCodePro. They decode the VIN and send the code, often within 30 minutes. For more details on choosing a PIN code provider, see our guide [link to article on how to safely obtain immobilizer PIN codes].

Q: Will this void my BYD warranty?

Performing advanced diagnostics like key programming can void your warranty if it causes a malfunction. However, using the LAUNCH X431 correctly — following manufacturer-specified procedures — does not alter non-related systems. That said, I recommend informing your dealer that you had a key programmed by a professional locksmith or technician. Most dealers are understanding as long as no damage occurred.

Q: What if I only have one key and want to add a second?

You do not need the “All Keys Lost” procedure. Use the Add Key function in the X431 IMMO menu. The car must be running (or at least in ignition-on mode), and you need the existing working key present inside the vehicle. This process takes about two minutes.

Conclusion: You’re Back in Control

Recovering from a BYD Seal all keys lost situation is stressful, but with the right tools and knowledge, it’s a solvable problem. The LAUNCH X431 Key Programmer is your most reliable partner for this task. Follow the steps carefully, keep a battery maintainer connected, and always have a backup key ready.

Next Steps:

If you haven’t already, purchase a LAUNCH X431 IMMO Elite or equivalent model with BYD IMMO support.
Contact a PIN code provider before you start the job.
Keep a spare key in a safe place — ideally not in the same location as your main keys.

Got stuck? Reply in the comments below with your tool version and the exact error message. We help our readers get back on the road.

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/