Changan Key Programming 

How to Program a Changan CS35 Plus Key with LAUNCH X431 | Step-by-Step Guide

• June 01, 2026
Learn how to program a new key for your Changan CS35 Plus using the LAUNCH X431. Step-by-step instructions, troubleshooting tips, and FAQs for immobilizer programming.

Published: June 1, 2026

Quick Answer: Programming a Changan CS35 Plus Key with LAUNCH X431

To program a new key for your Changan CS35 Plus using the LAUNCH X431, you need the "Immobilizer" or "Anti-Theft" function. Connect the tool, select your vehicle, navigate to Immobilizer > Key Programming > Add Key. The tool will guide you through a security access procedure, then you will place the new key in the ignition or the center console reader, and the tool will write the key data to the vehicle's ECU. Always ensure the new key is a compatible, uncut transponder blank.

Understanding the Requirements

Before you start pressing buttons, take a moment to gather the right materials. Nothing kills a programming session faster than a dead battery, a wrong key blank, or a missing security code.

What You Need

  • A compatible LAUNCH X431 tool – Models like the X431 PAD V, X431 PRO, X431 PRO Mini, and X431 V+ generally support Changan immobilizer functions. You must have the Changan software package installed and activated on your device. If your tool is a few years old, update it over Wi-Fi before proceeding.
  • The correct key blank – The Changan CS35 Plus uses a transponder chip, typically an 80-bit or 46-type chip. Do not assume any generic blank will work. Ask your supplier specifically for a "Changan CS35 Plus transponder key." The blade must be cut to match your vehicle’s door and ignition cylinder before you attempt to program the electronics.
  • At least one working original key – The "Add Key" procedure requires that you have a key already recognized by the car. If you have lost all keys, you will need the "All Keys Lost" function, which is more involved and may require dealer-level security codes.
  • A healthy vehicle battery – Low voltage is the number one cause of communication failures during programming. Measure the battery voltage; it should be at least 12.6 volts with the ignition off. If in doubt, connect a battery maintainer.

Why Preparation Matters

The immobilizer system in the CS35 Plus is designed to lock out unauthorized keys. If you start the process with a poor connection or a dying battery, the tool may fail to authenticate, and you could temporarily lock the ECU. That means a trip to the dealer for an expensive unlock. A few minutes of preparation saves hours of frustration.

Step-by-Step: Matching a New Key with LAUNCH X431

Follow these steps in order. Do not skip any, and do not rush. Each step builds on the previous one.

Step 1: Connect the LAUNCH X431 to the Vehicle

Plug the LAUNCH X431’s OBD-II connector into the vehicle’s diagnostic port. On the Changan CS35 Plus, this port is located under the dashboard on the driver’s side, near the hood release lever. You will hear a click when it is fully seated.

Insert one of your existing working keys into the ignition and turn it to the ON position (do not start the engine). This powers up the vehicle’s ECU and the OBD port.

Step 2: Launch the Diagnostic Software

Power on the LAUNCH X431. Wait for it to boot completely. From the home screen, tap Diagnosis. The tool will likely perform an Auto Scan to detect the vehicle automatically. If it does not, manually select Changan > CS35 Plus.

Let the tool scan all available systems. This takes about 30 to 60 seconds. When the scan completes, you will see a list of ECUs.

Step 3: Enter the Immobilizer System

From the system list, tap Immobilizer (sometimes labeled Anti-Theft System). The tool will request a Security Code.

  • Common default codes for Changan CS35 Plus: Try 123456, 0000, 168, or 000000.
  • If none of these work, the code may have been changed. In that case, look for a Read Code function within the Immobilizer menu. The LAUNCH X431 can often read the correct 4-digit or 6-digit code directly from the BCM.
  • If you still cannot get the code, you may need to contact a dealer with your VIN. Write down the code securely – you will need it again if you ever program another key.

Enter the correct code and tap OK.

Step 4: Navigate to Key Programming

Once inside the Immobilizer menu, select Key Programming. A submenu will appear with options like Add Key, Delete All Keys, and sometimes All Keys Lost.

For a simple key addition, choose Add Key. Do not select "Delete All Keys" unless you intend to wipe all keys from the ECU and start fresh. That option is risky because if you do not have all keys ready to program immediately, you could lock yourself out.

Step 5: Follow the On-Screen Prompts

The LAUNCH X431 will now display step-by-step instructions. They typically look like this:

  1. Turn ignition OFF and remove the current working key. Do exactly that.
  2. Insert the new uncut transponder key into the ignition cylinder (or place it on the center console key reader pad if your CS35 Plus has keyless start).
  3. Turn the ignition ON (engine off) with the new key.
  4. The tool will now communicate with the ECU to write the new key’s chip data. This can take 30 to 120 seconds. You will see a progress bar or a message like "Programming in progress."
  5. Once complete, the LAUNCH X431 will display "Key Learned Successfully" or "Programming Completed."

Do not turn the ignition off or disconnect the tool until you see that success message.

Step 6: Test the New Key

Remove the new key from the ignition. Insert your original working key and start the engine. It should run normally – this confirms the old key still works.

Now insert the newly programmed key. Start the engine. It should also start and run without any immobilizer warning light on the dashboard.

If the engine cranks but does not start, the chip programming did not take. You may need to repeat the procedure or check the key blank compatibility.

Troubleshooting Common Issues

Even with careful preparation, things can go wrong. Here are the most common problems and how to fix them.

"Connection Error" or "Communication Failure"

Likely cause: Loose OBD connector, low battery, or outdated software.

Fix:

  • Wiggle the OBD connector to ensure a solid connection.
  • Measure the vehicle battery voltage. If it is below 12.4V, connect a battery maintainer.
  • Update the LAUNCH X431 software via Wi-Fi. Go to Settings > Software Update and check for the latest Changan package.

"Security Code Incorrect"

Likely cause: You entered a wrong default code, or the code has been changed from the factory default.

Fix:

  • Try alternative codes: 000000, 1234, 168, or the last 4 digits of your VIN.
  • Use the Read Code function inside the Immobilizer menu. If the tool can read it, it will display the correct code.
  • If nothing works, you will need to obtain the code from a Changan dealer. Provide them with your VIN and proof of ownership.

"Key Not Learned" or "Programming Failed"

Likely cause: The new key blank has an incompatible transponder chip, or the chip is defective.

Fix:

  • Verify with your supplier that the blank is specifically for Changan CS35 Plus. Some generic blanks claim compatibility but fail during programming.
  • Try a different blank from a different batch.
  • If you have a key programmer that can read transponder IDs, check if the chip responds.

Remote Keyless Entry (RKE) Not Working After Programming

Explanation: The LAUNCH X431 immobilizer procedure programs only the engine start chip, not the remote door lock function. RKE is a separate system.

Fix:

  • Try a manual re-sync: Sit in the car with all doors closed. Insert the key into the ignition and turn to ON. Press and hold the Unlock button on the remote for 5 seconds. Then press the Lock button twice. Turn the ignition OFF and test the remote.
  • If that fails, the CS35 Plus may require a dedicated RKE Programming function within the LAUNCH X431. Navigate to Body Control Module > Remote Key Programming and follow the prompts.

Topical Deep Dive: Immobilizer Systems and Key Security

Understanding how the immobilizer works helps you debug problems and appreciate why the LAUNCH X431 is the right tool for the job.

How the CS35 Plus Immobilizer Works

Every original key for the Changan CS35 Plus contains a small transponder chip. When you insert the key and turn to ON, the vehicle’s ECU sends a challenge signal to the chip. The chip responds with a unique encrypted code. If the code matches one stored in the ECU’s memory, the ECU allows the engine to start. If not, the engine will crank but never fire.

When you program a new key using the LAUNCH X431, you are essentially adding that chip’s unique ID to the ECU’s allowed list. The tool handles the security handshake – the "security access" – that unlocks the ECU for writing.

Why LAUNCH X431 Over Generic Tools

Many generic OBD tools can read and clear fault codes, but they cannot perform the Security Access procedure required by Chinese domestic market (CDM) vehicles like the Changan. The LAUNCH X431 series uses a proprietary protocol that emulates the manufacturer’s diagnostic interface. This is why it can do things that a $50 code reader cannot.

For the CS35 Plus specifically, the LAUNCH X431 supports both Add Key and All Keys Lost procedures. The latter requires a higher subscription level but is available on most Pro and PAD models.

Risks of the Wrong Procedure

The biggest risk is selecting Delete All Keys when you only intended to add one key. This erases all existing keys from the ECU memory. If you then fail to program at least two new keys (some systems require a minimum of two), the ECU may become locked, and you will need a dealer-level tool or an EEPROM programmer to recover it.

Another risk is using a defective key blank. A cheap aftermarket blank may program successfully but then fail after a few weeks due to a weak transponder. Spending a little more on an OEM or high-quality aftermarket blank is worth the peace of mind.

Aftermarket vs. OEM Keys

OEM Changan keys are the safest choice. They are guaranteed to have the correct chip and proper build quality. Aftermarket blanks can save money, but quality varies widely. If you buy aftermarket, purchase from a reputable automotive locksmith supplier and ask specifically for 80-bit transponder blanks verified for Changan.

Frequently Asked Questions (FAQ)

Q: Do I need to cut the key before programming?
A: Yes. You must cut the metal blank to match the physical lock shape before starting the programming process. The programming only teaches the car to recognize the electronic chip inside the key.

Q: Can I program a key for a Changan CS35 Plus without the original key?
A: Yes, but it is much more difficult. The LAUNCH X431 may offer an "All Keys Lost" function, but this usually requires a longer procedure, a higher tool subscription level, and specific security codes derived from the vehicle's VIN.

Q: Will this procedure affect the remote keyless entry (RKE) function?
A: Not directly. Programming the immobilizer chip does not automatically program the remote door lock function. You often need to perform a separate remote sync procedure (see Section 3).

Q: My LAUNCH X431 says "Vehicle Not Supported." What can I do?
A: Ensure your software is updated. Check if your specific X431 model supports the "Changan" software pack. Some older X431 models may require a separate "GFS" (General Function Software) module.

Q: How many keys can I program to a CS35 Plus?
A: The system typically supports up to 4 or 5 keys. If you attempt to add more than the limit, the oldest key in the memory will be erased.

Q: The new key works in the ignition but the remote buttons don't work.
A: Try the manual re-sync method: sit in the car with all doors closed. Insert the key and turn to ON. Hold the Unlock button on the remote for 5 seconds. Press the Lock button twice. Turn the key OFF and test. If it fails, the remote receiver might have a separate programming procedure requiring the X431's "RKE Programming" function.

Final Tips for Success

  • Always keep your LAUNCH X431 software up to date. LAUNCH regularly releases updates for Chinese vehicle coverage, including Changan models.
  • If you are new to key programming, practice on a vehicle you own before attempting it on a customer’s car.
  • Document your security code once you find it. Store it in a secure place – you will need it again.
  • For complex situations like all keys lost, consider consulting an experienced automotive locksmith or diagnostic technician.

For more details on using the LAUNCH X431 for other vehicle diagnostics, check out our guide on [link to related guide on LAUNCH X431 basic diagnostics].

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/

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