RAM Trucks Programming 

Add Transponder Key to 2018+ Ram ProMaster City with LAUNCH X431

• June 16, 2026
Step-by-step guide to program a transponder key for a 2018+ Ram ProMaster City using LAUNCH X431 and FCA SGW bypass cable. Includes prerequisites, PIN retrieval, troubleshooting, and pro tips.

Quick Answer: Adding a Transponder Key to a 2018+ ProMaster City

To add a transponder key to a 2018+ Ram ProMaster City, you need a LAUNCH X431 with FCA SGW bypass cable, a compatible blank key (typically ID46 Gold), and the vehicle’s 4-digit security PIN. The process involves connecting the X431 via the SGW adapter, bypassing the security gateway, entering the immobilizer system, and using the Add Key function. If you fail the PIN entry three times, the immobilizer locks for 30 minutes. Successfully programmed keys will allow the engine to start and the dash security light to turn off after 2 seconds.

Introduction: Why Adding a Key Is Trickier Than You Think

If you own a 2018 or newer Ram ProMaster City and need a spare transponder key, you’ve probably discovered that your usual OBD-II scanner won’t cut it. Fiat Chrysler Automobiles (FCA) introduced a Security Gateway (SGW) on these models starting in 2018—a cybersecurity measure that blocks direct communication with the Body Control Module (BCM) and immobilizer system. Standard key programming tools that worked fine on older ProMaster City vans simply cannot talk to the security modules without a bypass.

That’s where the LAUNCH X431 steps in. Equipped with the FCA SGW access cable, this diagnostic platform becomes one of the few aftermarket solutions that can add a transponder key without a trip to the dealer. In this guide, I’ll walk you through the step-by-step procedure, explain the SGW bypass, and help you sidestep common pitfalls like PIN lockouts and wrong chip types.

This information is based on real-world experience supporting automotive workshops and locksmiths who regularly program keys for FCA vehicles. By the end, you’ll have a clear roadmap to successfully add a transponder key to your 2018+ Ram ProMaster City.

Understanding the FCA Security Gateway (SGW)

Why FCA Introduced SGW

Before 2018, thieves could plug a simple diagnostic tool into the OBD-II port and program a blank key to steal a vehicle within minutes. To combat this, FCA (now part of Stellantis) added a Security Gateway—a hardware and software barrier that requires authentication before any module can be read or written to. The SGW sits between the OBD port and the vehicle’s controller area network (CAN) bus, effectively filtering out unauthorized commands.

How SGW Affects Key Programming

When you try to access the immobilizer system directly through the OBD port, the SGW blocks the request. The tool will either show a “Communication Error” or simply refuse to enter the Immobilizer menu. Without a bypass, you cannot add, delete, or learn keys. This same gateway also protects other modules—like the ABS, airbag, and transmission control unit—but for key programming, the immobilizer (usually inside the BCM or PCM) is the target.

The LAUNCH X431 SGW Module

The LAUNCH X431 achieves bypass using an FCA SGW Access cable, a small adapter that plugs between the X431 main cable and the vehicle’s OBD-II port. This adapter includes electronics that mimic the authentication handshake required by the SGW. Once connected, the X431 can send the proper CAN messages to unlock the gateway. Without this specific cable, even a high-end aftermarket scanner will fail.

Vehicles affected beyond the ProMaster City: The same SGW system applies to many 2018+ FCA vehicles—Ram 1500/2500, Jeep Grand Cherokee, Dodge Durango, Chrysler Pacifica, and others. If you work on FCA vehicles frequently, the SGW cable is a must-have.

Prerequisites and Tool Requirements

Required Tools

Tool / Part Purpose Notes
LAUNCH X431 (V+, Pro, PAD VII, etc.) Diagnostic platform Must support J2534 pass-through and FCA SGW
FCA SGW Access cable Bypass security gateway Sold separately, not included with X431
Blank transponder key New key to program Use ID46 Gold (PCF7935) for most 2018+ models
Key cutter (optional) Cut blade to match lock Only if original key is lost or blade not available
Battery maintainer or charger Stabilize voltage during programming Low voltage can cause immobilizer corruption

Tip: To verify the correct chip type, use the X431 to read the existing key’s transponder ID. Most 2018+ ProMaster City vans use ID46 (PCF7935), but a few early models may use ID47. If you order the wrong blank, the programming will appear to succeed but the engine won’t start.

Vehicle Preparation

  • Battery voltage: Ensure the vehicle battery reads at least 12.5V. During key learning, the BCM and immobilizer draw extra current. If voltage drops below 11.5V during the process, the learning may fail—or worse, corrupt the immobilizer memory.
  • Key fob battery: If your new key includes a remote fob, insert a fresh battery. The remote learning process may be separate from transponder programming, but a dead fob battery can still cause confusion.
  • Security PIN: You’ll need the 4-digit security code. Common sources:
    • A dealership (often free if you prove ownership with registration)
    • A locksmith with access to FCA PIN databases
    • If you already have two working keys, some tools can extract the PIN (but this is not guaranteed with the X431)

Important Safety Note

Work in a well-ventilated area. Keep a second person nearby to help turn the ignition on/off quickly if needed. Never disconnect the X431 during the key learning phase—doing so may permanently lock the immobilizer, requiring dealer-level replacement.

Step-by-Step: Programming a New Transponder Key

Step 1: Connect and Set Up the LAUNCH X431

  1. Install the FCA SGW cable between the X431 main diagnostic cable and the vehicle’s OBD-II port. The cable has two ends—one plugs into the X431, the other into the car. Make sure it clicks securely.
  2. Turn the ignition off. Do not turn it on yet.
  3. Connect the X431 power (via OBD port) and wait for the tool to boot. The X431 will draw power from the vehicle battery.
  4. Launch the LAUNCH X431 app and select Diagnostic → FCA (USA) → Ram → ProMaster City.
  5. Choose model year (2018 or newer). If your X431 has VIN auto-detection, it may prompt you to confirm the identified vehicle. Always verify the VIN matches your van.

Common mistake: Selecting the wrong model year (e.g., 2017) will bypass the SGW detection and lead to communication failures. Double-check the year on your registration.

Step 2: Perform SGW Bypass

  1. Navigate to Security Gateway Access – This is usually found under Special Functions or System Selection. The exact menu name varies by X431 software version, but look for “SGW Bypass” or “Security Gateway.”
  2. Follow on-screen instructions. The LAUNCH X431 will typically ask you to perform a battery reset:
    • Disconnect the battery negative terminal for 2 minutes.
    • Reconnect the terminal.
    • Turn the ignition to ON (do not start).
  3. Wait for confirmation. The tool will tell you “SGW Bypass Successful” once the gateway unlocks. If you see “SGW Bypass Failed,” check the cable connection and try again.

Why this step matters: Without a successful SGW bypass, the Immobilizer system will not appear in the menu, or you’ll get a “Module Not Responding” error. Do not skip it.

Step 3: Access Immobilizer System

  1. Return to the main diagnostic menu after bypass success.
  2. Select Immobilizer or Anti-Theft System. On some X431 software versions, it’s under Body Control Module or PCM and labeled “Security.”
  3. Enter the 4-digit security PIN when prompted. The default from the factory is often 1234, but most 2018+ vehicles have a unique code set by the dealer. If you have the wrong code, you will see “Incorrect PIN.”
  4. If PIN fails three times, the immobilizer locks for 30 minutes. You cannot retry during this period. Leave the ignition on (position II) and wait exactly 30 minutes before retrying. Do not turn the ignition off or on repeatedly—that resets the timer.

Pro tip: If you don’t have the PIN, contact a dealer with your VIN. Many dealers will provide it over the phone for free, as long as you can prove ownership. Some online services (like CarDAQ-S2 or AutoKeyPro) can retrieve the PIN from the VIN for a small fee.

Step 4: Add the New Transponder Key

  1. Select Add Key from the immobilizer menu. If you see “Program Keys” instead, be careful—that option usually erases all existing keys and requires you to reprogram every key you own. “Add Key” simply adds a new key to the existing set (up to 8 keys total).
  2. Insert the new blank transponder key into the ignition and turn to the ON position (position II). Do not try to start the engine.
  3. Wait for the X431 to display “Learning” or “Key Added.” This process takes about 10–20 seconds. The dashboard security light may flash rapidly during learning.
  4. Remove the key and turn the ignition off.
  5. Test the new key by re-inserting it and turning to ON. The security light should illuminate for about 2 seconds and then turn off. If it stays on or flashes, the key was not learned correctly.

Troubleshooting: If “Learning” fails, the most common causes are:

  • Wrong chip type (ID46 vs ID47)
  • Low battery voltage during learning
  • Faulty blank key (try another from a trusted supplier)

Step 5: Verify and Clear DTCs

  1. Scan all modules using the X431 for Diagnostic Trouble Codes (DTCs). After key programming, you may see:
    • U0100 – Lost communication with ECM (often temporary)
    • B2106 – Immobilizer fault (can appear after programming)
  2. Clear all DTCs using the Clear Trouble Codes function.
  3. Test start the vehicle with the new key 2–3 times. The engine should crank and run normally.
  4. Test the old keys as well to ensure they still work. Adding a key does not erase existing keys, but it’s always good practice to verify.

Troubleshooting Common Issues

Symptom Possible Cause Fix
“SGW Bypass Failed” Incorrect cable connection, low battery voltage Reconnect cable, reset battery (disconnect negative 2 min). Check voltage >12.5V.
“Cannot read immobilizer” SGW not bypassed, wrong vehicle selection Repeat Step 2 with ignition on. Verify VIN matches model/year.
PIN entry fails repeatedly Wrong code source Contact dealer with VIN. Wait 30 min if locked out.
Key added but won’t start Chip type mismatch (e.g., ID46 vs ID48) Read existing key chip using X431. Order correct blank.
Engine starts but remote lock doesn’t work Transponder programmed, fob not learned Perform remote key fob programming separately (see your X431 menu under “Key Fob” or “Remote Control”).
Immobilizer locked for 30 minutes Too many PIN attempts Leave ignition on (position II) for exactly 30 minutes, then retry.
X431 says “Security Gateway Not Supported” Outdated firmware Update X431 via WiFi. If still unsupported, you may need a newer model or a third-party J2534 device like MongoosePro FCA.

Pro Tips for Success

  • Battery Power Stability: Use a battery maintainer that can supply at least 10A through the OBD port. A voltage drop during the learning phase is the #1 cause of failed programming on FCA vehicles.
  • Key Blank Source: Only buy blanks from reputable locksmith suppliers or manufacturer-authorized dealers. Counterfeit blanks often have incorrect chip programming or unstable transponder IDs.
  • Backup Existing Keys: If you have two working keys, program a third before any risky operation. Some tools offer a “Learn All Keys” function that erases all previous keys—if you only had one key and that fails, you’re locked out.
  • Firmware Update: FCA updates their SGW protocol every few months. Ensure your LAUNCH X431 has the latest software (connect to WiFi and check for updates) before starting the job. An outdated X431 may fail to communicate with newer vehicles.

Frequently Asked Questions (FAQ)

Q1: Can I use any LAUNCH X431 model for this procedure?

Only models with J2534 pass-through and FCA SGW support. The X431 V+, X431 Pro, X431 PAD VII, and newer X431 Euro Pro are all compatible. Check your tool’s menu for “SGW Access” or “Security Gateway.” Some older models may require a paid software subscription to enable the SGW function.

Q2: Do I need dealer software if I have the SGW cable?

No. The LAUNCH X431 with the SGW cable provides dealer-level access for key programming. However, you still need the 4-digit PIN code, which a dealer can provide (often free if you show ownership). The tool itself does not require a subscription for this specific function, but immobilizer coverage may vary by region.

Q3: Will adding a key erase the existing programmed keys?

It depends on the menu choice you make. Selecting Add Key typically adds a key without erasing others. Selecting Program Keys or Learn All Keys will erase all existing keys, and you must reprogram every key you own in one session. Always read the on-screen prompt carefully before confirming.

Q4: What if my ProMaster City doesn’t have a push-to-start button?

The procedure is identical for turn-key ignition. Insert the blank key and turn to ON (position II) for the learning step. Do not turn to START until after the key is programmed.

Q5: Can a locksmith use the X431 without the SGW cable?

No. The SGW cable is mandatory for 2018+ FCA vehicles. Without it, the tool cannot communicate with the BCM or immobilizer. The X431 alone will give a “No Communication” error.

Q6: My LAUNCH X431 says “Security Gateway Not Supported” – what now?

Update your X431 firmware to the latest version via WiFi. If the issue persists, your model may not support FCA SGW at all. In that case, you will need a newer X431 model or a third-party J2534 pass-through device like the MongoosePro FCA, which is specifically designed for FCA SGW bypass.

Q7: Is it possible to program a key without the original key?

Yes, if you have the 4-digit PIN code (obtained from the dealer or a locksmith using the VIN). Without the PIN, you cannot program any key, even if you have a working original. If you have at least one original key, you may be able to extract the PIN using special tools, but the X431 does not have this PIN extraction function built-in.

Q8: Will this work for the 2017 Ram ProMaster City?

Only 2018+ models have the Security Gateway. The 2015–2017 ProMaster City uses standard OBD access and does not require the SGW cable. For those years, a standard LAUNCH X431 can program keys without any bypass.

Q9: What is the cost for a professional to add a key?

Dealer prices typically range $100–$200. An independent automotive locksmith with SGW-capable tools will charge $80–$150. DIY cost is around $60–$120 for the blank key and tool subscription (if applicable). The SGW cable itself costs about $30–$60 and is reusable.

Conclusion: Your Spare Key Is Now Within Reach

Adding a transponder key to a 2018+ Ram ProMaster City doesn’t have to be a dealer-only affair. With the right preparation—a LAUNCH X431, the FCA SGW bypass cable, the correct blank key, and a valid security PIN—you can program a spare yourself in about 30 minutes. The most critical steps are the SGW bypass and the PIN entry. Get those right, and the rest flows smoothly.

Remember: patience is your best tool. If you’re locked out by PIN failures, wait the full 30 minutes. If a key fails to learn, check your voltage and chip type. And always, always verify that your X431 firmware is up to date before starting.

Have you successfully added a key to your ProMaster City using this method? Share your experience in the comments below—including any challenges you faced and how you solved them. For more

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