In simple terms, the car's (Built-in Systems Interface—the main computer) or the immobilizer system cannot recognize the key fob you are using to start the car, even if it is present in the dashboard slot or inside the cabin. Common Symptoms of B173D
Here is the most likely explanation, followed by a summary review of the actual vehicle you probably mean. b173d peugeot
If both keys fail and throw code B173D, the problem lies within the car's internal receiving network. Step 3: Perform a Full BSI Hard Reset In simple terms, the car's (Built-in Systems Interface—the
The antenna around the ignition barrel that reads the key might be faulty. Recommended Troubleshooting Steps Step 3: Perform a Full BSI Hard Reset
B173D cannot be fixed by disconnecting the battery, swapping fuses, or using an SRS reset tool alone. It requires component-level diagnosis and often physical replacement of the seat occupancy sensor mat plus calibration. If you don't have Diagbox, a specialist Peugeot/Citroën diagnostic shop is recommended.
An ounce of prevention is worth a pound of cure.