Swap out the old coin-cell battery inside the remote control for a high-quality replacement.

An "Electronic Anti-theft Fault" or "Economy Mode Active" message appearing on the dashboard.

: The internal antenna or the key reader unit (often located near the ignition or in the center console for hands-free systems) may be faulty or disconnected.

If possible, swap the Cylinder 4 glow plug with Cylinder 1. Clear the codes and restart.

This article will leave no stone unturned. We will explain exactly what this code means, the specific symptoms you will feel (and not feel), the step-by-step diagnostic process, the most likely culprits, and how to fix it permanently.

While rare for a single cylinder, some BlueHDi engines have a master fuse for the glow plug control unit. If this fuse blows, you will get multiple glow plug codes for all cylinders (B173C, B173D, B173E, B173F). If you only have B173D, the fuse is fine.

: A blown 10-amp fuse within the BSI unit can sometimes be the culprit behind communication failures [25].

: The physical coil or reader in the steering column or center console may be damaged.

In some Peugeot models, B173D is linked to the or the "Battery Charge Status" module.

AdBlue fluid can crystallize in cold weather or if the vehicle is unused, clogging the injector and triggering this fault. ⚡ Secondary Cause: Energy Management

Possible accompanying codes: (Immobilizer reading error) or B173A (Driver door presence sensor fault). Causes of the B173D Code

Understanding Peugeot Fault Code B173D: Key, Immobilizer, and BSI Solutions

: Message displays such as "Key Not Detected," "Electrical Circuit Fault," or "Anti-Theft Fault" populate the multi-function display.

When the BSI logs this diagnostic code, you will usually notice immediate security and electrical hiccups:

: Use an OBD2 scanner to clear the code and see if it returns. If it persists, a specialist may need to check the wiring between the antenna and the BSI.

Immobilizer / Keyless Entry & Start (ADML) / Built-in Systems Interface (BSI).