or the hands-free remote control. It is a body-related code ("B" prefix) often logged by the Built-in Systems Interface (BSI)
: Messages such as "Electronic anti-theft faulty" or "Key not detected" may appear on the multi-function display. Potential Causes Several factors can trigger the B173D fault: Faulty Key or Transponder
The Peugeot BSI is the brain of the vehicle's cabin electronics, managing everything from central locking to transponder validation.
If your vehicle’s dashboard displays messages like "Key Not Detected" or "Immobilizer Fault," and an OBD2 diagnostic scan confirms code B173D, a systematic troubleshooting approach can help identify and resolve the underlying issue. Core Symptoms of Fault Code B173D
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. b173d peugeot
: The BSI unit may have experienced a software glitch, often caused by a low battery or incorrect battery reconnection. Wiring Faults
Fault code is a body control / airbag system diagnostic trouble code (DTC) specific to Peugeot (and other PSA group vehicles like Citroën, DS, and sometimes Opel). It indicates a malfunction within the Occupant Classification System (OCS) — specifically, the system is unable to reliably confirm the "seat occupied" status of the front passenger seat .
Understanding Peugeot Fault Code B173D: Key, Immobilizer, and BSI Solutions
Do not assume the battery is good. A battery that has enough voltage for the central locking (short range) might not have enough power for the immobilizer communication (shorter range). Step 3: Check Vehicle Battery Voltage or the hands-free remote control
Fault codes that appear and disappear randomly often trace back to poor earth (ground) connections. The engine ECU, BSI, and ABS module share critical ground points. A corroded or loose earth strap can cause voltage fluctuations that result in communication faults and immobilizer codes.
PSA Group vehicles are known for corroded connectors, especially in lower bumper areas exposed to water spray. Broken wires, bent pins, or oxidation at the 3-pin connector are frequent culprits.
When this fault triggers, the vehicle's Built-in Systems Interface (BSI)—the central body control module—is unable to validate the encrypted security code sent by your key transponder or keyless access module. Consequently, the engine immobilizer remains active, often preventing the engine from starting entirely.
However, don’t ignore the code indefinitely. If it’s accompanied by the B1808 immobilizer code, your car may refuse to start at the worst possible moment. A few hours of methodical diagnostics now can save you from a tow truck call and a hefty repair bill later. If your vehicle’s dashboard displays messages like "Key
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. Errore B173D B1808 B2EA0 B1003 - Citro n-Club e DS Forum
This code is often seen when a Peugeot refuses to start, but its cause can range from a simple dead battery to complex electronic desyncing: Key Recognition:
If power or ground is missing, check fuses and wiring continuity.
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