If you own a Peugeot and have encountered the fault code B173D, you are likely dealing with an issue related to your vehicle’s door mirrors. This code is specific to the Body Control Module (BCM) and relates to the electrical functioning of the mirror adjustment or folding mechanism.
Below is a detailed breakdown of what this code means, its symptoms, causes, and how to resolve it.
In Peugeot diagnostic systems (and generic OBD-II translations), the code B173D is typically defined as:
In simpler terms, the car's computer (ECU) has sent a signal to fold or unfold the mirrors, but the electrical circuit was not completed. The system detects a break in the "loop," meaning the electricity is not reaching the mirror motor or is not returning to the sensor.
Before spending money on parts, try resetting the BSI properly.
Please confirm: Did you mean the Peugeot 173 D vintage car, or is "B173D" written on a specific part of a newer Peugeot (e.g., 206, 307, 508)? If you tell me the exact location (engine block, door jamb, fuse box), I can identify the part.
In the world of Peugeot and Citroën (PSA Group) diagnostics, fault code B173D is a specific error related to the vehicle's immobilizer system. If your car is showing this code, it typically means the Built-in Systems Interface (BSI) is having trouble identifying the mechanical or electronic key. What Does Code B173D Mean?
The official definition for B173D is an error identifying the mechanical/electronic key or hands-free remote control located in the reader. When this happens, you may experience: "Key not detected" warnings on the dashboard. Engine failing to start or "cranking but not firing". Central locking malfunctions. Common Causes b173d peugeot
Weak Key Fob Battery: Often the simplest culprit, a dying battery in your remote can prevent the reader from "seeing" the key.
Transponder Fault: The chip inside the key itself may be damaged or faulty.
Antenna/Wiring Issues: The internal antenna that reads the key signal or the wiring connecting it to the BSI may be compromised.
BSI Communication Glitch: The BSI (the car's central "brain") may have lost its coding or is failing to communicate with the engine ECU. Troubleshooting Steps Before heading to a specialist, try these DIY fixes: Electrical circuit fault: have your vehicle repaired
code is indeed an "interesting piece" of Peugeot (and Citroën) diagnostics, as it points directly to a breakdown in the conversation between the car and its key. Technically, it is defined as a Fault in identifying the mechanical/electronic key or the hands-free remote control present in the reader. Why it's a "Head-Scratcher"
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:
The car’s Built-in Systems Interface (BSI) cannot verify the "identity" of the key, often resulting in a "Key Not Detected" message or a complete refusal to crank. Chain Reaction: It frequently appears alongside Quick Summary
(Engine management ECU immobiliser reading error), which means the immobiliser is staying locked because it hasn't received the "all clear" from the key reader. Common Culprits Key Fob Battery:
The most common and easiest fix; a weak battery can prevent the hands-free signal from being strong enough for the reader. The "BSI Glitch":
French car electronics sometimes get "confused." Mechanics often perform a
(a specific sequence of battery disconnection and waiting) to clear these ghost errors. Antenna/Reader Failure:
The physical coil or antenna around the ignition barrel (or the hands-free slot) may have failed, meaning it can't "hear" even a perfectly good key. Are you currently dealing with a non-starting vehicle, or are you just digging into the technical side of Peugeot's diagnostic systems?
In Peugeot and Citroën vehicles, the fault code B173D specifically indicates a failure in identifying the mechanical or electronic key, or the hands-free remote control located in the reader. This body control fault is managed by the Built-in Systems Interface (BSI), which is the central computer responsible for security and electronics. Understanding the B173D Fault
When this code is triggered, the car's immobilizer system fails to recognize the security signature of the key. This often results in: "Key Not Detected" warnings on the dashboard. Central locking malfunctions. Fault Code: B173D System: Body Control Module (BCM)
Engine "No Start" conditions where the vehicle turns over but refuses to fire. Common Causes
The B173D code can range from a minor maintenance issue to a significant electrical failure:
Key Fob Battery: A weak or dead battery in the remote can prevent the reader from receiving a valid signal.
Antenna/Reader Failure: The physical coil or reader in the steering column or center console may be damaged.
BSI Communication Errors: Software glitches or hardware failure within the BSI unit itself.
Battery Voltage Issues: Low vehicle battery voltage can cause "phantom" BSI codes.
Corrupted Data: If the battery was disconnected improperly, the BSI may "lose" the coding for the keys. Troubleshooting Steps
Before taking the car to a dealership, you can perform these basic checks: Electrical circuit fault: have your vehicle repaired
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