B173d Peugeot Work |top| Jun 2026

The central computer (BSI) might have internal errors or corrupted software that needs a reset.

This article provides a comprehensive guide to the B173D fault code for Peugeot vehicles. It covers what the code means, how it manifests, the common underlying causes, a systematic diagnostic approach, and step‑by‑step solutions to help you resolve the issue effectively.

Your brake lights may stay on constantly or fail to light up at all. Root Causes of B173D b173d peugeot work

Crucially, many owners report that —for example, the lights still work, the windows still operate, and the engine runs fine. This indicates that the problem is often a logical or voltage‑related fault, rather than a physical failure of each component.

The Peugeot fault code primarily indicates a failure in identifying the mechanical or electronic key (including hands-free remotes) within the vehicle's reader . This error is often logged by the Built-in Systems Interface (BSI) , which serves as the central control unit managing immobilizer functions. Understanding Fault Code B173D The central computer (BSI) might have internal errors

failure to identify the mechanical/electronic key or hands-free remote control . This code is typically stored in the Built-in Systems Interface (BSI) and can prevent the vehicle from starting. Technical Overview: Fault Code B173D

If your vehicle has stored code B173D, you may experience the following symptoms: Your brake lights may stay on constantly or

Twist the switch counter-clockwise to unlock it from the bracket. Disconnect the wiring plug.

: The vehicle might start perfectly fine on a cold morning but fail to start entirely after a short trip to a shop.

: Drivers will face a "no crank, no start" condition, frequently paired with a dashboard notification reading "Key Not Detected". Primary Causes of Key Detection Failures