B173d Peugeot

B173D is a straightforward electrical fault indicating a broken connection to your folding mirrors. It is rarely dangerous, but it is a nuisance that can prevent you from parking in tight spaces. If you have basic electrical knowledge, checking the wiring between the door and the mirror is the best place to start.

Note: Always disconnect the vehicle battery before attempting any electrical repairs to avoid short circuits or airbag faults.

The "story" of B173D in a Peugeot is essentially a tale of a car that has forgotten its owner. In technical terms, B173D is a diagnostic fault code that indicates a failure to identify the mechanical/electronic key or the remote control [25]. What happens to the car?

When this code is triggered, the vehicle's Built-in Systems Interface (BSI) or immobilizer unit cannot verify the security signal from your key. This usually results in:

The engine failing to start because the immobilizer keeps the fuel system or starter locked.

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

The central locking possibly becoming unresponsive or intermittent [25]. Common "Characters" in the Problem

The root cause is rarely a broken engine and is usually one of these electrical "gremlins":

The Key Fob Battery: A weak battery in the remote can prevent the car from "hearing" the electronic handshake it needs to start.

The Car Battery: Low voltage in the main car battery can cause the BSI (the car's "brain") to glitch and lose synchronization with the keys.

The Transponder Coil: The small ring around the ignition barrel that "reads" your key might be faulty or disconnected.

BSI Software Glitches: Sometimes the car's computer simply needs a "hard reboot" to recognize its programming again. The "Fix" (How to resolve B173D)

The BSI Reset: Many Peugeot owners solve this by performing a specific "battery reset" procedure. This involves disconnecting the battery, waiting, and then following a sequence (like turning on headlights through an open window) to "wake up" the BSI properly.

Key Resynchronization: Putting the key in the ignition, turning it to the "ON" position, and holding the lock button for 10 seconds can sometimes re-pair the electronic signal.

Check Fuses: A blown 10-amp fuse within the BSI unit can sometimes be the culprit behind communication failures [25]. b173d peugeot

If these DIY steps don't work, a technician usually needs to use a Peugeot Planet or Diagbox scanner to clear the code and manually re-code the keys to the vehicle [25].

Are you currently unable to start your car, or did you just see this code during a scan?

Engine failure service code indicates everything is wrong in the car

Fault code B173D on a Peugeot indicates an "Error identifying the mechanical/electronic key or hands-free remote control". This means your car's Built-in Systems Interface (BSI) or Body Control Module is struggling to recognize the signal from your key or transponder.

Here is a breakdown of what this code means and how to address it. Symptoms of B173D

No Start: The engine may fail to crank or start because the immobilizer is active.

Key Not Detected: A warning message appearing on the dashboard or touchscreen.

Central Locking Issues: Intermittent failure to lock or unlock the vehicle using the remote.

Service Light: An orange spanner light or general "Electrical circuit fault" message. Common Causes

Weak Key Battery: The most frequent cause; the signal is too weak for the car to pick up.

Faulty Key Fob: The transponder chip inside the key may be damaged or de-synchronized.

BSI Module Glitch: The car's main computer (BSI) may have a software "hang-up".

Interference: External radio signals or a poor vehicle battery can cause communication errors. How to Fix It

Replace the Key Fob Battery: This is the easiest and cheapest first step. B173D is a straightforward electrical fault indicating a

Try Your Spare Key: If the spare works, the problem is likely with your primary key's hardware. Perform a BSI Reset (Soft Reboot): Open the driver's window and ensure all doors are closed. Switch off the ignition and remove the key.

Wait 3 minutes, then disconnect the car's main battery for 15 seconds. Reconnect and wait 10 seconds (don't touch anything).

Turn on the side lights through the window to "wake up" the system, then try the ignition.

Check Vehicle Battery Voltage: Low vehicle battery voltage (below 12V12 cap V ) often triggers false immobilizer codes. ✅ Summary

B173D is a manufacturer-specific code for key identification failure. It usually points to a dead key battery or a module communication error rather than a major mechanical engine failure. If you need more help, could you tell me:

What is the specific model and year of your Peugeot (e.g., 3008, 2021)? Does the car start and run, or is it currently stranded? Are there other fault codes appearing on your scanner?

Peugeot Warning Lights: Dashboard Symbols, Meanings & Next Steps

The Peugeot fault code B173D identifies a failure in the recognition of the mechanical or electronic key (or remote control) by the vehicle's immobiliser system. This diagnostic trouble code (DTC) is commonly associated with Peugeot and Citroën vehicles, particularly when the car fails to start or displays a "key not detected" warning. Understanding B173D: Causes and Symptoms

When this code is triggered, the Built-in Systems Interface (BSI) cannot verify the security signal from your key. Common triggers include:

Key Battery Issues: A weak or dead battery in the key fob is the most frequent cause.

Immobiliser Antenna Fault: The transponder coil around the ignition barrel or the keyless entry antenna may be failing to transmit the signal.

BSI Communication Errors: Software glitches or hardware faults within the BSI module can lead to intermittent key recognition failures.

Vehicle Battery Voltage: A worn-out car battery can cause "phantom" faults across multiple systems, including the key recognition circuit. Troubleshooting Steps

If your Peugeot is throwing the B173D code, you can follow these steps to narrow down the issue: What happens to the car

Replace the Key Battery: Start with the simplest fix by installing a fresh battery in your remote.

Test the Spare Key: If a second key works, the issue is likely with the internal chip or hardware of the first key rather than the car's system.

Perform a BSI Reset: This is a standard "soft reset" for Peugeot/Citroën electronics. You can find specific procedures for this on community resources like the Peugeot Forums or via video tutorials like the BSI Reset Procedure.

Check Vehicle Battery Health: Have your main car battery tested. If it is more than 3–5 years old, low voltage during startup can trigger B173D.

Diagnostic Scanning: 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.

Are you currently unable to start the car, or is this just an intermittent warning on your dashboard?

It seems you are asking for a review of the Peugeot "B173D" — however, no production Peugeot car model is named B173D.

Here is the most likely explanation, followed by a summary review of the actual vehicle you probably mean.

Before spending money on parts, try resetting the BSI properly.

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.

To fix this code, a mechanic or a confident DIYer will typically follow these steps:

Peugeot BlueHDi engines are notorious for carbon buildup. Because the glow plugs extend into the combustion chamber, they become crusted with hard, black carbon. This carbon can:

The AQS is usually located behind the front bumper, near the radiator grille. Road salt, dirt, dead insects, or excessive wax from car washes can block the sensor’s inlet, causing it to read incorrectly. Sometimes, a simple cleaning solves the problem.