B173d Peugeot Access
B173D Fault Code Definition & - The Automotive Technician
In rare cases (2015-2017 models), Peugeot released software updates to address false b173d alerts. Your local Peugeot dealer can update the BSI firmware. Cost is typically 0.5 hours of labor.
Switch off all electronics, close all doors, and remove the key from the ignition. for the BSI to go into "sleep mode." Disconnect the vehicle battery and wait at least 15 seconds Reconnect the battery and wait 10 seconds without touching anything.
In French and Spanish Peugeot forums, the same code is described as "Défaut d'identification de la clé mécanique/électronique ou de la télécommande" and "Fallo al identificar la llave mecánica/electrónica o el mando a distancia" . b173d peugeot
The code is a classic, predictable failure on modern Peugeot, Citroen, and DS diesel engines. While the code sounds like a complex body control module error, it is almost always a simple electrical fault in the cylinder 4 glow plug circuit.
If linked to the battery, replacing the main or auxiliary battery typically solves the issue. ⚠️ Potential Impact
: The vehicle starts perfectly on some days but rejects the key entirely on others. B173D Fault Code Definition & - The Automotive
Peugeot electronics are notoriously sensitive to voltage drops. If the main 12V vehicle battery drops below 12.5 volts, the BSI may fail to initialize its security modules properly during startup, logging a false B173D identifier error. 4. BSI Corruptions or Desynchronization
Below is a detailed breakdown of what this code means, its symptoms, causes, and how to resolve it.
The physical slot where you insert the key can become dirty, dusty, or have bent pins, preventing communication. Switch off all electronics, close all doors, and
. This diagnostic trouble code (DTC) is categorized as a body fault and is managed directly by the vehicle’s central computer, known as the Built-in Systems Interface (BSI). When this error occurs, it breaks the vehicle’s security handshake, triggering security warnings and often leaving the driver stranded with a car that refuses to start.
(often written as 173D)
In older diesels, glow plugs only activated for 10–30 seconds before starting the engine to heat the combustion chamber. Once the engine was running, the glow plugs turned off.
Attempt to use your backup second key. If the vehicle starts seamlessly with the second key, the issue is isolated to your primary key's transponder chip or physical circuit board. Step 2: Utilize the Mechanical Backup Reader Slot