Step-by-step guide to program a BYD Dolphin smart key fob using the LAUNCH X431. Learn PIN retrieval, add keys, troubleshoot issues, and more.

How to Match a Smart Key Fob on BYD Dolphin with the LAUNCH X431 Key Programmer

Last Updated: May 26, 2026

Quick Answer

To match a smart key fob to a BYD Dolphin using the LAUNCH X431, you need a compatible X431 tablet (PRO, PAD VII, or higher), the latest BYD software, and a dealer-level or locksmith subscription. Connect the device to the OBD-II port, select the correct model, navigate to Immobilizer/Key Programming, enter or read the vehicle's PIN code, and follow the on-screen prompts to add or replace the key. The entire process typically takes 15–30 minutes. If you don't have the PIN, the X431 can read it from the BCM or ECU in most cases.

Understanding the BYD Dolphin Smart Key System

The BYD Dolphin is a modern electric hatchback that relies on a passive entry and push-to-start system. Unlike traditional keys, the Dolphin uses encrypted digital communication between the smart key fob and the Body Control Module (BCM). The car detects the key when it is within range—typically a few feet from the door handle—and allows you to unlock and start the vehicle without physically inserting anything.

Two types of keys are commonly used:

Card-style smart keys – Slim, credit-card-sized fobs that fit in a wallet.
Remote fobs – Traditional key-shaped remotes with lock/unlock buttons.

Both communicate via radio frequency (RF) and near-field communication (NFC). The BCM verifies the key’s unique ID against its stored list. If the ID doesn’t match or the key is not programmed, the immobilizer will prevent the engine from starting. This is why proper key programming is essential—and why the LAUNCH X431 is such a valuable tool for this job.

Prerequisites for Key Programming

Before diving into the procedure, make sure you have everything in place. Missing a single requirement can waste time or lock you out completely.

Required Tools

Tool	Notes
LAUNCH X431 (PRO, PAD VII, X431 V+, or equivalent)	Must have a working VCI (vehicle communication interface).
Latest BYD software	Update via Wi-Fi before starting. Check for BYD key programming database updates.
Valid subscription	Dealer-level or Locksmith subscription is mandatory. Basic subscriptions often lock this feature.

Vehicle Preparation

Battery voltage – The car’s 12V auxiliary battery (not the main drive battery) must be above 12.5V. If it’s low, use a trickle charger. Low voltage is a leading cause of communication failures.
At least one working key – If you are adding a new key, keep the original fob inside the car. For “All Keys Lost” scenarios, the procedure is different and more involved.
New key fobs – They must be compatible with the Dolphin. Aftermarket knock-offs sometimes fail. If you are reusing a used key, the X431 can erase its previous pairing first.

PIN Code Requirement

Every BYD Dolphin has a unique PIN code (usually 4 or 5 digits) that authorizes key programming. You need this PIN to proceed. Here are the three ways to get it:

Security card – Comes with the vehicle at purchase. Check the glovebox or owner’s manual wallet.
Dealer – Contact a BYD dealer with proof of ownership and the VIN. They can provide the PIN.
Read via X431 – Many BYD models allow the LAUNCH X431 to extract the PIN from the BCM or ECU. This is the most common method for locksmiths.

If you cannot obtain the PIN, key programming is impossible.

Step-by-Step Key Programming Procedure

This procedure assumes you have a working original key and want to add a new one. I will also touch on “All Keys Lost” in a separate note.

Step 1: Connect the LAUNCH X431 and Identify the Vehicle

Plug the X431 VCI into the OBD-II port. On the BYD Dolphin, this port is located under the driver’s side dashboard, near the hood release. You don’t need to remove any panels—just push the connector in until it clicks.

Turn on the tablet and open the Diagnostics app. The X431 will automatically search for a vehicle. If it doesn’t, tap the Auto Scan option.

From the menu:

Select BYD
Select Dolphin
Choose the correct model year and engine type (for the Dolphin, it’s always electric, but they may ask for the specific variant like “Dolphin 2023” or “Dolphin 2024”).

The device will read the vehicle’s VIN and load the appropriate diagnostic system.

Step 2: Navigate to Immobilizer / Key Programming

After the initial identification, you’ll enter the System Selection screen. Look for:

Body Control Module (BCM)
Or Immobilizer
Or Smart Key System

The exact name varies by software version. On most recent versions, select BCM → Special Functions → Key Programming.

Inside the key programming menu, you’ll see options like:

Add Key
Replace Key
All Keys Lost
Delete Keys

Choose the one that matches your situation.

Step 3: Retrieve or Enter the PIN Code

The X431 will now prompt you for the PIN. If you already have it (from the security card or dealer), type it in.

If you don’t have the PIN, look for a Read PIN button within the same menu. Tap it. The tool will attempt to extract the PIN from the BCM or ECU. This may take 2–5 minutes. The X431 communicates with the module and decodes the stored security data.

Troubleshooting tip: If PIN read fails, try a different system path—sometimes the PIN is stored in the ECU rather than the BCM. Go back to System Selection and choose Engine Control Module (ECU) → Read Security Code. On BYD vehicles, both locations are common.

Step 4: Add or Program the New Key

With the PIN entered, the screen will show a list of currently programmed keys (e.g., Key 1, Key 2, Key 3). If you have an original key working, it will be listed as Key 1. Select Add Key.

The X431 will then instruct you to place the new key fob in a specific location inside the car. For the BYD Dolphin, the programming area is usually the center console cup holder or the NFC reader area near the gear selector. Look for a small key icon or a marked spot—some models have a circular area with an antenna symbol.

Follow these typical on-screen prompts:

Place the new key fob in the programming zone.
Press the start button (without pressing the brake pedal) once. The dashboard should light up.
Wait for the system to learn the key. The instrument cluster may display “Key Detected” or “New Key Learned.”
The X431 will confirm that the key has been added. It will show the new key number (e.g., Key 2 or Key 3).

If you are in an “All Keys Lost” scenario, the process is similar but will erase all existing key data first. You will need to program two keys minimum (some systems require it). The X431 will guide you through a series of steps that involve reading the BCM, initializing it, and enrolling new keys one by one.

Step 5: Test and Exit

Once the X431 reports success, disconnect the tool. Test the new key immediately:

Lock and unlock the doors using the remote buttons.
Open the door and close it, then press the start button (with the brake pedal) to start the engine.
Walk away and approach again to confirm passive entry works.

If the engine starts and the doors respond, you’re done. If the dashboard shows “Key Not Detected,” the programming did not take. Go back to Step 4 and repeat, making sure the key is placed correctly in the antenna zone.

Troubleshooting Common Issues

Even with a good tool, problems can arise. Here are the most frequent ones and how to solve them.

“Communication Failure” Error

This usually means the X431 cannot talk to the BCM. Causes and fixes:

Loose OBD-II connection – Unplug and reconnect the VCI. Try a different VCI cable if available.
Low vehicle battery – Charge the 12V battery or connect a jump starter while programming.
Outdated software – Update the X431 firmware via Wi-Fi. Go to Settings → Firmware Update and install the latest version.
Wrong vehicle selection – Double-check that you selected the exact Dolphin model and year. A mismatch can block communication.

Wrong PIN Code

If you entered a PIN and the tool rejects it, try these:

Read the PIN again using the BCM or ECU option. Sometimes module communication is intermittent—a second attempt often works.
Check the security card – The PIN might be printed on a small plastic card. If the card is missing, contact a dealer.
Use the VIN – Some online databases (accessible via the X431) can look up the PIN using the VIN, but this requires a premium subscription.

Key Not Recognized After Programming

This is frustrating but usually fixable.

Check key compatibility – Aftermarket keys may fail the encryption handshake. If possible, use an original BYD part.
Battery in the key fob – Replace the CR2032 battery inside the key. Even a new key can have a weak battery from sitting on a shelf.
Incorrect key placement – The antenna zone may be smaller than you think. Try holding the key directly against the start button or the marked area for 10 seconds.
Delete and reprogram – Use the X431 to delete the failed key and try adding it again.

All Keys Lost Scenario Fails

If you have zero working keys and the X431 cannot complete the procedure:

Verify subscription – Make sure your X431 subscription explicitly covers “All Keys Lost” for BYD. Some lower tiers lock this feature.
Check software update – Early versions of the BYD software had bugs for All Keys Lost. Update to the latest.
Alternative method – On some Dolphin models, you need to perform a BCM initialization before key enrollment. Look for an “Initialize BCM” option in the special functions menu, then retry key programming.

If you are stuck, referring to the X431’s online database (accessible via the tablet) often provides model-specific workarounds.

Frequently Asked Questions

How do I obtain the PIN for a BYD Dolphin?

You can read the PIN using the LAUNCH X431 (via BCM or ECU), find it on the security card that came with the vehicle, or request it from a BYD dealer after providing proof of ownership. The dealer PIN is usually free if you are the registered owner.

Can I program a used smart key fob to my BYD Dolphin?

Yes, as long as the key is not locked to another vehicle. The LAUNCH X431 can erase the previous key data before programming it to your car. Simply choose the “Delete Keys” option first, then add the used key as a new one.

What if I have lost all keys for the BYD Dolphin?

The LAUNCH X431 supports “All Keys Lost” mode, but you will need the vehicle’s PIN. The process takes longer (up to 45 minutes) and may require accessing the BCM to manually enroll a new key. You will also need to program at least two keys on some models.

How long does the programming take?

Typically 15–30 minutes, depending on whether you already have the PIN and how quickly the software loads. Reading the PIN from the BCM adds 2–5 minutes. All Keys Lost scenarios can take 30–45 minutes.

Do I need professional assistance, or can I do this myself?

If you have a compatible LAUNCH X431 with the correct subscription and the PIN, an experienced DIYer can follow the steps. However, mistakes—like entering the wrong PIN repeatedly—can lock the immobilizer system and require dealer intervention. If you are not confident, hiring a professional locksmith or visiting a BYD dealer is safer.

Is the LAUNCH X431 compatible with right-hand drive BYD Dolphins?

Yes, the software is region-agnostic. Select the correct market (e.g., Australia, Thailand, or Europe) during the diagnostic session. The programming procedure is identical for left-hand and right-hand drive models.

Will the programming affect my existing keys?

No. Existing keys remain functional unless you specifically choose to delete them. Adding a new key simply increases the total number of recognized keys (e.g., from Key 1 to Key 2).

For similar key programming guides on other EV models, check out our article on [link to related guide on matching keys for BYD Atto 3]. If you need help choosing the right diagnostic tool, see our comparison of [link to LAUNCH X431 models and subscriptions].

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/

How to Match a Smart Key Fob on BYD Dolphin with LAUNCH X431