The fault code is a minor, non-critical electrical issue that plagues the PSA platform. While it is annoying to see a warning light on your dashboard, the repair is straightforward and inexpensive when approached methodically.
If the spare key works, the issue is with the first fob (the chip is dead). If neither works, the problem is within the car's system (reader or BSI). 3. Check the Key Slot Reader
in a Peugeot context refers to a specific diagnostic trouble code rather than a vehicle model. It indicates an issue where the car's Built-in Systems Interface (BSI) or immobilizer cannot recognize the key signal. Fault Code B173D Overview
The internal receiver slot or the proximity antennas hidden inside the center console or dashboard fail to read the transponder chip. b173d peugeot
To help me tailor advice for your specific vehicle, what of Peugeot are you working on, and does it use a traditional physical turn-key or a push-button start ? Share public link
If the vehicle starts cleanly with the secondary key, your primary key's transponder chip is damaged or desynchronized, requiring a locksmith to clone or re-program it.
If the BSI is corrupted, it may need to be updated, reconfigured, or replaced by a specialist. The fault code is a minor, non-critical electrical
: The immobilizer may remain active, preventing the engine management ECU from unlocking the vehicle for operation.
in the context of Peugeot refers to a specific diagnostic trouble code (DTC)
in Peugeot vehicles indicates a communication failure between the vehicle’s security system and the key. Specifically, it means the car is struggling to identify either the mechanical/electronic key or the hands-free remote control when it is in the reader. Symptoms and Causes If neither works, the problem is within the
The wiring harness that connects the glow plug control unit to the four glow plugs sits directly on top of a hot diesel engine. Over time (60,000+ miles), the insulation becomes brittle. The wire leading to Cylinder 4 often rubs against the engine cover or a fuel line, snapping internally. You may see no external damage, but a continuity test will reveal the break.
Disconnect the negative terminal of the 12V vehicle battery and wait .
A low 12V car battery can cause weird BSI issues. Ensure the car battery is healthy. Step 4: Perform a "BSI Reset" Sometimes the BSI just needs a power cycle. Lower the driver's window. Turn off the ignition, remove the key, and close all doors. Wait 3 minutes (until the BSI goes to sleep). Disconnect the negative terminal of the car battery. Wait 5 minutes. Reconnect the battery. Wait another 3 minutes before trying to start the car. Step 5: Check Antenna Connectors
: B173D is rarely found alone; it is frequently stored alongside related codes like B1808 (Engine management ECU immobilizer reading error) or B173A (Driver's door presence detection error). 🔍 Common Root Causes