Learn how to program a Peugeot 108 City Car key using Launch X431 transponder learning. Step-by-step guide, troubleshooting tips, and FAQs.

Quick Answer / Key Takeaway

Programming a Peugeot 108 City Car key with a Launch X431 transponder learning tool is a straightforward process that does not require a working original key. The X431 (with compatible software, such as X431 V or PAD series) can read the vehicle’s PIN, program new transponder chips, and synchronize remote functions. The entire procedure takes about 10–15 minutes and typically involves selecting the correct vehicle model, connecting to the OBD-II port, reading security data, and following on-screen prompts to add or replace keys.

Introduction

If you own a Peugeot 108 (2014–present), you already know that its key is more than just a piece of metal. Each key contains a small RFID transponder chip that communicates with the vehicle's immobiliser system. Without that chip, the engine simply won't start. Add the remote locking function, and you have a key that handles both security and convenience.

But what happens when you lose all your keys, need a spare, or your key fob stops working? Many owners assume they must visit a dealership and pay a premium. However, with the right tools—specifically a Launch X431 diagnostic scanner equipped with transponder learning capabilities—you can program a new key yourself. I've seen DIYers and small workshop technicians succeed with this approach, saving both time and money.

The Launch X431 is a multi-brand diagnostic platform that goes far beyond reading engine fault codes. Its transponder programming module allows you to read PIN codes, add or delete keys, and program remotes for hundreds of vehicles, including the Peugeot 108. It's important to understand the difference between transponder learning (which writes the chip data) and remote key coding (which syncs the lock/unlock buttons). The X431 handles both, but the procedure for each is slightly different.

What You Need Before Starting

Before you begin, gather these essentials:

Launch X431 device – Models like the X431 V, V+, or PAD VII with the “Key Programming” or “Immobiliser” function enabled. Ensure your software is updated to the latest version.
Blank key that matches your Peugeot 108 – Check the blade profile (typically HU66 or HU83), transponder chip type (commonly Texas Instruments 4C or PCF7935), and remote frequency (433 MHz is standard for most markets).
OBD-II connection cable – Supplied with the X431.
Vehicle battery fully charged – A minimum of 12.5V is recommended. Low voltage can cause communication errors.
Stable internet connection – The X431 may need to download vehicle-specific data if not already cached.
Optional: PIN code – In most cases, the X431 can read the PIN automatically. However, for some early 2014 models, you may need to extract it via the BSI (Body Control Module).

Pro tip: I always keep a spare blank key on hand. Occasionally, a defective chip slips through, so having a backup saves a trip back to the supplier.

Step‑by‑Step Guide: Programming a New Key

Follow these steps carefully. The Launch X431 provides on-screen guidance, but understanding what happens at each stage helps you avoid mistakes.

Step 1: Prepare the X431 and Connect to Vehicle

Power on your Launch X431. From the main menu, tap Transponder Learning (or Key Program depending on your firmware version). Select Peugeot from the brand list, then choose 108 or City Car from the model selection.

Plug the OBD-II cable into the vehicle's diagnostic port, located under the dashboard on the driver's side. Turn the ignition to the ON position (engine off). The tool should power on automatically once connected.

Step 2: Read Vehicle Information and Security Data

The X431 will automatically read the VIN, ECU part number, and immobiliser type. If prompted, enter the vehicle's mileage or follow instructions to read the PIN. On most Peugeot 108 models, the tool can decrypt the security code via OBD without any extra steps. This process typically takes 1–3 minutes.

Step 3: Choose the Programming Function

From the menu, select either:

Add Key – Use this if you have at least one working key. Insert the working key into the ignition, turn it ON, then insert the new key within 10 seconds.
Lost All Keys – Use this if no existing key works. The tool will guide you through a longer procedure that usually requires entering the PIN and programming the transponder chip on the new key directly.

I recommend the “Lost All Keys” option even if you have one working key, because it ensures every key in your possession is properly synchronized. However, if you're just adding a spare, “Add Key” is faster.

Step 4: Program the Transponder Chip

Hold the new blank key close to the X431’s transponder antenna. On many Launch units, this antenna is a small loop built into the OBD cable. On newer models, it may be a separate coil that plugs into the tablet. Follow the on-screen prompts—the tool will write the chip data to the key.

After successful writing, the tool will ask you to insert the new key into the ignition and turn it to the ON position for 5 seconds. This step confirms that the immobiliser recognizes the chip.

Step 5: Program Remote Key Functions (if applicable)

Transponder programming allows the engine to start, but the remote locking buttons won't work until you sync them. After completing Step 4, the X431 usually offers a Learn Remote or Add Remote function.

Press the lock or unlock button on the new key fob while the tool is in learning mode. The vehicle may respond by flashing the hazard lights or sounding a beep. If that doesn't happen, the tool will still display a confirmation message.

Step 6: Verify All Functions

Remove the key from the ignition. Test the remote by locking and unlocking the doors from a short distance. Then start the engine—it should crank and run without issue. Cycle the ignition off and on two more times to finalize the learning. If everything works, you're done.

Troubleshooting Common Errors

Even with the right tools, issues can arise. Here are the most common problems and how to resolve them.

Error: “Cannot Read PIN” or “Security Access Denied”

Ensure the ignition is ON (not just accessory mode).
Check for aftermarket immobilisers or alarm systems that may block communication.
Update your X431 software to the latest version.
On some 108 models, the PIN is stored in the BSI. Try selecting Read PIN by BSI if available in the tool menu.

Transponder Learning Fails (“Write Error” or “No Response”)

Confirm that your blank key contains the correct chip type. For most Peugeot 108 models, the chip is a PCF7935 or Texas Instruments 4C.
Hold the key directly against the X431 antenna—remove any key rings or metal objects that could interfere.
Try a different blank key. Defective chips are rare but do happen.
If you're using an older X431, the transponder antenna may be in the OBD cable, not the tablet itself. Make sure the key is touching the correct spot.

Remote Does Not Sync After Transponder Programming

Verify the remote frequency. Most Peugeot 108 models use 433 MHz, but some export versions use 315 MHz.
Re-enter remote learning mode by repeating Step 5. Sometimes the tool requires a second attempt.
Some 108 models require a specific button sequence inside the vehicle (e.g., turn ignition ON then press lock/unlock three times). Check the tool's instructions for any alternative method.

Key Starts Car but Remote Not Working

The remote battery might be discharged—replace the coin cell (CR2032) and try again.
The remote learning step may have been accidentally skipped. Reconnect the X431 and run only the Remote Learning sub-function.

FAQ

Do I need a working key to program a new one with the Launch X431?

No. The tool supports both “Add Key” (with one working key) and “Lost All Keys” procedures. For lost all keys, it will read the PIN directly via OBD.

Can I use the X431 to program a used or second‑hand key from another Peugeot?

Generally no. A used key’s transponder chip has been “married” to its previous car. You would need to erase the chip (if possible) with a dedicated programmer or buy a blank key.

How long does the battery on the X431 last during key programming?

Most X431 tablets have a battery life of 3–5 hours. If the battery is low, connect the provided charger while working.

Does the Launch X431 work on Peugeot 108 models from all years?

Yes, from 2014 onwards. Some early 2014 models may require a different software path (e.g., select “Peugeot 107” if 108 is not listed—the immobiliser system is similar).

Is it safe to program keys myself, or should I use a professional locksmith?

The X431 is designed for professional use, but many DIYers succeed by following on-screen prompts. Risks include bricking the immobiliser if the procedure is interrupted (avoid turning ignition off mid-process). If a fault occurs, a dealer tool may be needed to recover.

Can I program a remote without the transponder chip?

No – the remote control function depends on the key’s body, but the engine immobiliser requires the transponder chip. Program the transponder first, then the remote.

Why does my X431 say “Model Not Supported”?

Ensure your X431 has the “Transponder Learning” add-on installed (some models require an additional subscription). Also update to the latest software version – the Peugeot 108 was added in a 2022 update.

What if I accidentally program the wrong key?

You can use the “Delete All Keys” function in the X431, then re‑program only the correct keys. Always keep at least one working key available.

Conclusion

The Launch X431 turns what used to be a dealership-only job into a manageable DIY task. With the correct blank key, an updated tool, and a little patience, you can program a new Peugeot 108 City Car key in under 20 minutes. Whether you're replacing a lost key or adding a spare, the process is logical and well-supported by the X431's software.

A few final tips: always keep your X431 updated, use high-quality blank keys, and if you hit a roadblock, try disconnecting the car battery for 10 minutes to reset the BSI, then retry the procedure. For more details on choosing the right diagnostic tool for your workshop, check out our [guide to multi-brand scanners for European vehicles].

If you're new to transponder programming, start with a simple "Add Key" scenario before attempting a "Lost All Keys" job. And remember—practice makes perfect. After a few successful attempts, you'll wonder why you ever considered paying a locksmith.

Last updated: May 10, 2026

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/

Program Peugeot 108 Key with Launch X431 | Step-by-Step Guide