Learn how to program a spare key for your Mitsubishi ASX using a LAUNCH X431. Step-by-step guide including PIN retrieval, troubleshooting, and tips.

Published: June 15, 2026

How to Add a Spare Key to a Mitsubishi ASX with LAUNCH X431

Quick Answer (AI Overview): To add a spare key to a Mitsubishi ASX using a LAUNCH X431, connect the tool, navigate to the Immobilizer or Special Function menu, select Key Programming, and follow the on-screen prompts. This process generally requires the original working key and a specific security access code (found via VIN lookup or from the dealer). The LAUNCH X431 generates the necessary PIN code automatically for most ASX models (2010+), bypassing the need for a separate dealer visit.

Security Check: Ensure the Master Key is present, as the ASX system generally requires it to authorize new key additions.

Losing your only Mitsubishi ASX key or needing a spare doesn't have to mean a costly tow to the dealership. With a professional-grade diagnostic tool like the LAUNCH X431, you can program a new transponder key yourself—saving time and money. This guide walks you through every step, from preparation to troubleshooting, so you can add a spare key with confidence.

Prerequisites & Preparation

Before diving into the programming sequence, gather everything you’ll need. Missing a component can stop the process mid-way or, worse, lock you out of the immobilizer system.

Diagnostic Tool: A LAUNCH X431 series tool – X431 V, PAD, Pro, or X431 EURO all work. Make sure your software is up to date; the X431 typically prompts you to update before starting diagnostics.
Vehicle: Mitsubishi ASX (model years 2010–present). This also applies to the Outlander Sport in some markets, as they share the same immobilizer system.
Power Supply: A stable 12V battery is critical. Warning: A low battery can brick the immobilizer during programming. If your battery voltage reads below 12.4V, connect a battery maintainer or a jump starter pack.
Keys:
- Master Key: The original working key (usually with the remote fob). You will need this to authorize new key addition.
- New Key: A compatible uncut transponder key. For pre-2018 models, get an ID46 (Texas Instruments 4C) chip. For 2018+ models, you need an ID47 (Philips) chip. Using the wrong chip will cause failure and a 5-minute immobilizer lockout.
Internet Connection: Required for the X431 to download the specific software package and access the online PIN retrieval database. A stable Wi‑Fi or mobile hotspot is fine.

Connecting the LAUNCH X431 to the Mitsubishi ASX

Proper connection ensures reliable communication between the tool and the vehicle’s ECU. Follow these steps:

Locate the OBD2 Port: It’s under the driver’s side dashboard, usually near the fuse box or above the footwell. Plug the X431’s OBD2 cable into the port.
Turn Ignition ON: Insert your master key (or have it ready) and turn the ignition to the “ON” position (dashboard lights up, engine off). Do not crank the engine.
Power On the X431: Press the power button on the tablet/diagnostic unit. Wait for the system to boot completely.
Select Vehicle: Tap Diagnostics > Asia > Mitsubishi > ASX (or use the VIN auto-detect feature if available).

The X431 will then download the necessary software if it hasn’t been downloaded already. This may take a minute or two – be patient.

Accessing the Immobilizer System

The key programming function is hidden inside the special functions menu, not the standard engine or ABS menu. Here’s how to find it:

Navigate After VIN Confirmation: Once the VIN is confirmed, look for Immobilizer or Security on the main diagnostic menu. This may be listed under a “System” list.
Select Special Function: Choose Special Function or Action Test (the exact wording varies by X431 software version).
Find Key Option: Scroll down the list. You should see Key Programming or Add Spare Key. Tap on it.

If you don’t see the immobilizer option at all, your X431 may need a software update. Connect to the internet and run the update function before proceeding.

Retrieving the PIN Code (The Critical Step)

The Mitsubishi ASX immobilizer requires a 4‑digit Security Code (PIN) to authorize key addition. Without it, you can’t proceed. The LAUNCH X431 automates this step for most models, but you must understand both methods.

Method A – Automatic Retrieval: The X431 will prompt you to read the security code. Select Read PIN or Get Security Code by VIN. The tool connects to the cloud and retrieves the code within seconds. This works for the majority of ASX models (2010–2022).
Method B – Manual Input: If automatic retrieval fails (due to a weak internet connection or an unsupported model year), you must enter the code manually from the dealer or a paid VIN‑based lookup service (e.g., NASTF or AutoKeyPro). You will need proof of ownership and the VIN.

Important: Write down the PIN displayed on the screen. You may need it if the process fails and resets. Store it safely.

The Key Programming Procedure (Step‑by‑Step)

Follow these steps exactly. The ASX immobilizer is sensitive to timing and sequence.

Insert Master Key: Put the original working key into the ignition.
Confirm Authenticity: The tool will ask you to turn the key to “ON” then back to “OFF” to confirm the Master Key is present. Do exactly that.
Enter PIN: Input the 4‑digit PIN code retrieved in the previous step.
Confirm Number of Keys: The system will ask how many keys you want to program. Select “2” (your original + the new spare) . This ensures the original key remains active.
- Crucial Note: If you select “1,” the system may overwrite the Master Key, leaving you locked out. Always choose the total number of keys you want to have.
Program New Key:
- The screen will say “Insert New Key” .
- Remove the Master Key from the ignition.
- Quickly insert the new spare key and turn it to “ON” (position 2). Do not leave it in position 1 too long.
- Wait for the tool to display “Programming Successful” .
Finalize: Turn the new key to OFF. Remove it.

The whole process from step 1 to step 6 takes about 2–3 minutes. If you see any error, refer to the troubleshooting section below.

Verification & Troubleshooting

Verifying Success

Test Start: Insert the new key and start the engine. It should crank and run normally.
Remote Check (if applicable): If the new key has remote buttons, check lock/unlock functions. The remote fob programming is a separate process (covered in the next section).

Troubleshooting Common Errors

Error Message	Likely Cause	How to Fix
Cannot Communicate with Immobilizer	Loose OBD2 connection or software glitch.	Turn ignition off, wait 10 seconds, reconnect the X431 cable firmly, and restart the software.
Incorrect PIN Code	Automatic PIN read failed, or the code is wrong.	Disconnect internet, reconnect, and re‑run the VIN lookup. If still failing, obtain the PIN from a dealer or a paid service.
Number of Keys Exceeded	ASX supports only 4 keys. If you already have 4 active keys, you must erase some first.	Use the Erase All Keys function (found in Immobilizer > Special Function), then program the 2 keys you want (original + new).
Bricked Immobilizer (Engine Cranks but No Start)	Power loss during programming.	Use the LAUNCH X431 Immobilizer Initialization or ECU Reset function. If that fails, you may need a J2534 passthrough tool or a dealer visit.

Prevention Tip: Always connect a battery maintainer if your car battery is old or below 12.4V. A sudden voltage drop during programming is the number one cause of immobilizer bricks.

Alternative Methods & Special Cases

For Remote Fob Programming (Separate Process)

The LAUNCH X431 can usually program remote keyless entry fobs under Central Locking > Action Test > Remote Key Registration. The typical procedure (varies by model year) is:

Lock all doors manually using the driver’s door lock.
Insert the key into the ignition and turn it ON and OFF rapidly 4 times (within 10 seconds).
Press the lock button on the new remote fob. The doors should lock/unlock to confirm registration.
Repeat for each additional remote.

For 2020+ ASX Models (Keyless Go / Proximity Keys)

These models use proximity keys (push‑to‑start). The programming logic is the same, but the X431 requires a newer software update. The “Master Key” must be physically present near the steering column NFC reader (usually under the steering wheel). The tool will guide you through a similar PIN‑based process.

Using the X431 for Other Mitsubishi Models

The same methods apply to Mitsubishi Outlander, Lancer, Montero, and Pajero (2008–2022). The immobilizer system is similar, though the PIN retrieval method may differ slightly. For more details on other models, see our guide on [link to related guide on using LAUNCH X431 for Mitsubishi key programming].

Frequently Asked Questions (FAQ)

Can I program a Mitsubishi ASX key without an X431?

No. The ASX immobilizer is encrypted. You need a dealer‑level scanner (like the X431), a dedicated locksmith tool, or an Autel unit. A simple $20 OBD2 fault code reader cannot perform key programming.

Do I need a special chip for the new key?

Yes. The ASX typically uses a Texas Instruments 4C (ID46) chip for pre‑2018 models, or a Philips (ID47) chip for 2018+. Using the wrong chip will cause failure and a potential 5‑minute immobilizer lockout. Always confirm the chip type with your key supplier or a local locksmith.

How much money does this save vs. a dealership?

A dealer charges $150–$300+ for a single Mitsubishi key cut and programming. Using the X431, you only pay for the blank key ($15–$40) and the cut. The tool pays for itself after 2–3 uses.

Will the LAUNCH X431 erase my existing keys?

Only if you select Replace All Keys instead of Add Key or if you choose a number of keys lower than the number currently registered. Always select the total count of keys you want to have (old + new).

What if the "Read PIN" function fails?

Ensure your X431 software is fully updated. If it still fails, you must obtain the 4‑digit security code from a Mitsubishi dealer (requires proof of ownership and VIN), or use a paid PIN retrieval service like NASTF or AutoKeyPro.

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 Add a Spare Key to a Mitsubishi ASX with LAUNCH X431 | Step-by-Step Guide