The official Mitsubishi service manuals, which serve as the primary "verified" source for diagnosing this code, list the following as the most probable causes:
"Transponder registered for another vehicle" or "Already learned by another vehicle".
It is critical to determine which system your specific Mitsubishi model is referencing before beginning any repair work. The following table summarizes the two interpretations:
regarding the challenges of programming used Mitsubishi ETACS modules. Watch a brief technical demonstration on fixing immobilizer key issues related to this error type. Are you seeing this code after replacing a key or after a battery/module change AI responses may include mistakes. Learn more mitsubishi b1766 verified
| Aspect | | Other Brands (e.g., GM) | | :--- | :--- | :--- | | System Affected | Immobilizer / Anti-Theft System | Body Control Module (BCM) / Interior Comfort Systems | | Definition | "Already learned by other vehicle" / "Transponder registered for other vehicle" | "Seat Driver Forward Circuit Open" | | Primary Symptom | Engine cranks but will not start, security light flashing | Driver's seat cannot move forward, check engine light on |
A verified diagnosis of DTC B1766 almost always points to a key or immobilizer issue. To prevent this problem, consider the following:
If the code returns immediately after verifying the keys and network, the ECU internal memory is corrupted. Remove the compromised ETACS-ECU unit. The official Mitsubishi service manuals, which serve as
Repair costs vary widely based on the issue. A simple wiring repair might cost between $100 and $200, while replacing a seat motor or control module could run from $400 to $1,000 or more when parts and labor are included.
Plug the scanner into the OBD2 port beneath the driver-side dashboard.
If you own two Mitsubishi vehicles or have borrowed a key from a similar model, using the wrong key will trigger this code. Watch a brief technical demonstration on fixing immobilizer
Navigate to the "Immobilizer" or "ETACS" live data parameters on your scanner. Look for the following values: Number of Keys Learned Key Code Status (e.g., "Invalid", "Foreign", or "Locked") CAN Bus Line Integrity Step 3: Rule Out Module Damage
Check your PLC software, check connections, and reset the alarm.