Mechanic Wiki: How to Program a Mitsubishi Colt Plus Key with LAUNCH X431 (Step-by-Step Guide)

Learn how to program a Mitsubishi Colt Plus key or remote using a LAUNCH X431 scanner. Step-by-step immobilizer and key fob programming guide for DIYers.

Last Updated: June 15, 2026

How to Program a Mitsubishi Colt Plus Key with LAUNCH X431 (Step-by-Step Guide)

Quick Answer

You can program a new key or remote for a Mitsubishi Colt Plus using a LAUNCH X431 by accessing the Immobilizer section under Special Functions. The process involves reading the PIN code (or using a 4-digit code from the key tag), then selecting “Program Keys” or “Key Learning.” The X431 must have the Mitsubishi software package installed and an active online subscription for PIN decryption. If you already have two working keys, you may also use a manual OBD procedure; otherwise, the X431 is required.

Introduction: Why Use a LAUNCH X431 for the Colt Plus?

If you’ve lost your only Mitsubishi Colt Plus key or need to add a spare, you’ve probably discovered that a simple hardware-store cut won’t do the trick. The Colt Plus uses a transponder chip inside the key that communicates with the vehicle’s immobilizer system. Without programming that chip into the ECU, the engine simply won’t start.

A LAUNCH X431 diagnostic tool—whether it’s the X431 V+, PAD, PRO, or another model—gives you dealer-level access to the immobilizer functions without a trip to the dealership. I’ve used X431 units on dozens of Mitsubishi models, and the Colt Plus procedure is one of the most straightforward once you know the steps. This guide walks you through the entire process, from preparation to troubleshooting, so you can get back on the road confidently.

1. Preparation & Requirements

Before you plug in the X431, a little prep goes a long way. Skipping these steps is the #1 reason DIYers run into “Communication Failure” or “Invalid PIN” errors.

Tool Compatibility

Model check: Most LAUNCH X431 series tools (X431 V+, PAD III, PAD VII, PRO, etc.) support Mitsubishi immobilizer functions as long as the Mitsubishi software is up to date. Connect your X431 to Wi-Fi and run the software update tool before starting. If you’re using an older X431 with outdated firmware, some menus may not appear.

Vehicle Specifics

This guide applies to the Mitsubishi Colt Plus produced roughly between 2004 and 2012. Later models (post-2015) use a more complex security algorithm that may require locksmith-level software.

Key type matters: The Colt Plus uses either a standard transponder key (with or without remote buttons) or a remote flip key. The immobilizer chip is separate from the remote fob—programming one does not automatically program the other. You’ll need to perform two distinct procedures.

OBD Connection & Ignition

Plug the X431 cable firmly into the OBD-II port beneath the driver’s side dashboard.
Turn the ignition to the ON position (engine off). The dashboard lights should come on.
Battery voltage: The vehicle battery must be above 12V. If it’s weak, connect a battery charger. Low voltage during programming can corrupt the immobilizer data.

2. Step-by-Step: Immobilizer Key Programming

This procedure programs the transponder chip inside the key so the engine will crank and start. Follow these steps exactly—each timing matters.

Step 1: Vehicle Connection & System Selection

Connect the LAUNCH X431 to the OBD port and turn the ignition ON.
From the main menu, select Mitsubishi → Colt Plus.
Navigate to Immobilizer System. If you don’t see it directly, go to Engine ECU and look for the Immobilizer submenu.

Pro tip: On some X431 versions, the Immobilizer menu is labeled “Security System” or “Anti-Theft System.” If you still can’t find it, run a System Scan—the tool will list all available ECUs.

Step 2: Read Security (PIN) Code

Select Read PIN Code or Security Code.
The X431 will communicate with the immobilizer module and attempt to retrieve the 4-digit PIN.
If the tool fails: Check the original key tag. Many Colt Plus keys came with a small silver sticker that has a 4-digit code printed on it. Enter this code manually when prompted.

What if the PIN still won’t read? The X431 often requires an active online subscription to decrypt the PIN. Make sure your X431 has a Wi-Fi connection and that your subscription covers Mitsubishi online security access. Without it, the tool may show a blank field.

Step 3: Key Programming Procedure

Once the PIN is verified, go to Special Functions → Key Registration.

Option A: Adding a key (you already have one or two working keys)

Select Add Key.
The X431 will ask how many keys you want to operate (including existing ones). For example, if you already have two keys and want to add one, enter 3.
Follow the on-screen prompts: Turn the ignition OFF, remove the X431, insert the first key, and turn it to ON. Wait 5 seconds. Repeat for each subsequent key.

Option B: All keys lost (you have zero working keys)

Select Erase All Keys first. This clears all stored transponder IDs from the ECU.
Then proceed with Key Registration and add your new key(s). The vehicle will not start until at least one key is programmed.

Important: Do not select “Erase All Keys” if you have working keys unless you are prepared to reprogram all keys. I’ve seen owners accidentally erase everything and then have to tow the car to a dealership—don’t be that person.

Step 4: Remote Key Fob (Door Lock) Programming

The remote fob (lock/unlock buttons) uses a separate system from the immobilizer. Even after the transponder is programmed, you must pair the remote separately.

Return to the main menu and select Central Locking → Remote Control Registration.
Follow the X431 prompts: Within 10 seconds, press the LOCK button on the remote three times.
The turn signals should flash once to confirm.
Test: Lock and unlock the doors with the fob.

If the fob doesn’t respond after registration, replace the battery inside the remote with a fresh CR2032 coin cell. Low battery voltage is the most common cause of failed remote pairing.

3. Common Troubleshooting & Pitfalls

Even with the right tool, you may hit a snag. Here are the most frequent issues and how to solve them.

Error / Symptom	Likely Cause	Solution
“Communication Failure”	OBD port fuse blown (often shared with cigarette lighter fuse)	Check fuse box under dash. Replace if blown.
“Invalid PIN”	X431 subscription expired or no Internet	Connect to Wi-Fi and ensure online security access is active.
Key turns ignition but engine won’t start	Transponder chip not learned	Repeat Step 3 (Key Registration). Ensure ignition stays ON for full 60 seconds if prompted.
Remote works manually (key lock cylinder) but fob doesn’t	Dead fob battery or fob not paired	Replace CR2032 battery and re-run Remote Control Registration.
Anti-theft light stays on solid	Immobilizer failed to complete learning	Turn ignition OFF and back ON. Wait 60 seconds without starting. Then try again.

4. Context & Topical Depth

Why This Works

The LAUNCH X431 communicates directly with the Mitsubishi immobilizer module using the vehicle’s diagnostic protocol. The Colt Plus uses a rolling code system—each time the key communicates with the ECU, a new code is generated. The X431 can retrieve the current PIN and simulate the learning process that the dealer’s MUT-III tool would perform.

OEM vs. Aftermarket Keys

You can use aftermarket keys as long as they are:

Physically cut to match your Colt Plus lock cylinders.
Equipped with a compatible transponder chip (most Colt Plus models use a T5 or T6 chip).
Have a remote fob circuit board that matches the frequency (usually 433 MHz for Mitsubishi).

Cheap blank keys from online marketplaces often have poor-quality transponders. I recommend using an OEM-grade blank from a reputable supplier—it will save you headaches.

When to Call a Locksmith

The X431 method works well for Colt Plus models up to about 2012. If your vehicle is a 2015 or newer, the security algorithm is significantly more complex. In those cases, even some X431 software versions may fail to read the PIN. If you’ve tried the above steps twice and still get errors, it’s time to call an automotive locksmith who has factory-level tools like the Autel IM608 or Launch X431 Pro with J2534 pass-through.

5. Frequently Asked Questions (FAQ)

Can I program a Mitsubishi Colt Plus key without the LAUNCH X431?

Yes, if you already have two working keys, you can use the manual sequence: insert and remove the key five times within 10 seconds, then press the lock button on the new remote. This adds a third key. If you have one or zero keys, the X431 or a dealer tool is mandatory.

Does the LAUNCH X431 work for the Colt Plus Smart Key (Push-to-Start)?

Yes, but the procedure is different. Instead of the standard Immobilizer menu, you need to select Smart Key Registration. You may also need to place the smart key in a specific slot near the steering column (check your owner’s manual). The X431 will guide you through a series of ignition cycles.

Will the X431 erase my existing keys if I make a mistake?

Yes, if you select “Erase All Keys” accidentally, the ECU forgets every transponder ID. The engine will not start until you reprogram all keys. Always use “Add Key” if you have working keys.

Why does my new key turn the ignition but the engine won’t start?

The transponder chip hasn’t been programmed to the immobilizer. The remote door lock function is separate—completing Step 4 doesn’t affect the immobilizer. Go back and run Key Registration (Step 3) correctly.

Do I need an internet subscription for LAUNCH X431 to do this?

Yes. Reading the PIN code and programming functions typically require an active Online Security Access subscription. A local software file alone won’t be enough. Make sure your X431 has a stable Wi-Fi connection before starting.

Final Thoughts

Programming a Mitsubishi Colt Plus key with a LAUNCH X431 is a job that most DIY mechanics can handle with patience and the correct steps. The key is to prepare properly—update your software, check your battery voltage, and understand the difference between immobilizer programming and remote pairing. If you run into trouble, revisit the troubleshooting table above. And if all else fails, a professional locksmith with dealer-level tools can finish the job in minutes.

For more step-by-step diagnostic guides, check out our articles on [link to related guide on programming other Mitsubishi models] and [link to related guide on LAUNCH X431 immobilizer functions].

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/