. Because the immobilizer doesn't get the correct "handshake" signal, it prevents the engine from cranking or firing to protect against theft. Common Symptoms Non-starting engine: The car may not even attempt to crank. "Key Not Detected" messages:
Troubleshooting the B173D Peugeot work code requires a systematic approach to identify the root cause of the problem. Here are the steps to follow:
Some owners have discovered that the act of plugging in an OBD diagnostic tool at a test centre can trigger B173D and other codes. This suggests a momentary interruption of CAN bus communications. b173d peugeot work
This is critical. A battery with a dead cell (voltage drops below 10V during cranking) will trigger B173D falsely.
Poorly installed aftermarket devices (e.g., dashcams, aftermarket alarms, mobile phone chargers, or OBD (On-Board Diagnostics) dongles left plugged in) can draw power or generate electrical noise that disturbs the BSI. This is critical
The fault code on a Peugeot indicates a failure to identify the mechanical or electronic key (or hands-free remote) . This is typically an immobilizer-related issue where the car’s Built-in Systems Interface (BSI) cannot verify the key's security signal, often resulting in a "key not detected" message or a car that cranks but will not start. Immediate Troubleshooting Steps
: Often, this is caused by a weak key fob battery , a faulty antenna, or communication issues between the key and the BSI. It can also be triggered if the car battery was disconnected without following the proper procedure. Recommended Troubleshooting Steps 💡 When buying a replacement switch
: Ensure the main vehicle battery is fully charged and the connections are clean and tight.
: Replace the coin battery in your remote and try using a spare key if available.
💡 When buying a replacement switch, always use an OEM (Original Equipment Manufacturer) part. Peugeots are notoriously sensitive to the resistance levels in aftermarket electronic components, and a cheap switch may trigger the B173D code again within weeks. If you'd like more specific help, tell me: