Step-by-Step Guide to Peugeot & Citroën BCM (BSI) Repair

If you own a Peugeot 207, Peugeot 307, or Citroën C3, chances are you’ve heard of BSI problems. The BSI (Built-in Systems Interface) is the French equivalent of the Body Control Module (BCM) — it’s the “nerve centre” of the vehicle’s electronics.

When the BSI develops faults, you may experience frustrating issues like:

• Central locking not responding

• Dashboard lights flickering or going blank

• Headlights or wipers acting unpredictably

• Car failing to start after a flat battery or jump-start

The good news? Many BSI/BCM faults can be repaired. In this blog, we’ll walk you through the step-by-step repair process.

🔎 Symptoms of BSI/BCM Failure in Peugeot & Citroën

Before attempting a repair, confirm the signs of failure:

• Intermittent or total electrical failure

• Immobiliser/key recognition issues

• Random alarms or indicator flashes

• No communication with diagnostic tools

• Car not starting after battery replacement or voltage spike

🛠️ Tools & Equipment Needed

• OBD2 diagnostic tool (preferably Peugeot Planet or Lexia for Citroën)

• Trim removal tools & screwdrivers

• Soldering iron, flux, and solder

• Multimeter for circuit testing

• Isopropyl alcohol & brush (for cleaning corrosion)

• Replacement chips/components (if needed)

⚡ Step-by-Step BSI/BCM Repair

1. Run a Diagnostic Scan

Use a Peugeot Planet 2000 (PP2000) or Lexia/Diagbox tool to scan the car.
Look for communication errors with the BSI. This helps confirm whether the issue is BCM-related.

2. Disconnect the Battery Properly

Peugeot and Citroën vehicles are sensitive to voltage spikes. Follow the official BSI reset procedure:

1. Switch off all lights and remove the key.

2. Wait 3 minutes before disconnecting the battery.

3. Disconnect the negative terminal first.

This prevents corruption of the BSI software.

3. Locate & Remove the BSI

In Peugeot 207, 307, and Citroën C3 models, the BSI is usually found behind the glovebox or dashboard area.

• Remove the glovebox or trim panels.

• Carefully disconnect the wiring harnesses (note their positions).

• Remove the BSI unit from its housing.

4. Open & Inspect the Circuit Board

Place the BSI on a clean workbench.
Check for:

• Water ingress (a very common issue in PSA vehicles)

• Corroded pins or connectors

• Burnt or cracked solder joints

• Damaged microchips

5. Repair the BSI

• Clean the board with isopropyl alcohol if corrosion is present.

• Reflow solder joints that look cracked or dull.

• Replace faulty components (e.g., relays, resistors, or capacitors).

• If the software has become corrupted, reprogramming with factory tools may be necessary.

6. Reinstall & Test

• Refit the BSI into its housing and reconnect all plugs securely.

• Reconnect the battery (positive first, then negative).

• Run the diagnostic tool again, clear fault codes, and test:

  • Central locking

  • Lights and indicators

  • Wipers

  • Engine start/immobiliser

If everything works, the repair is successful.

🚨 Important Notes

• Always follow the BSI reset procedure when disconnecting or reconnecting the battery. Skipping this step can corrupt the BSI software.

• If the BSI is too damaged, a professional repair or cloning service (transferring data to a donor unit) may be required.

✅ Final Thoughts

BSI/BCM problems are common in Peugeot and Citroën models like the 207, 307, and C3. With patience and the right tools, many issues can be repaired by cleaning, soldering, and reprogramming the module.

However, if you’re not confident with electronics, it’s always best to send the unit to a specialist BSI repair service in the UK — this ensures the immobiliser data and coding remain intact.

• Peugeot 207 BSI repair

• Peugeot 307 BCM fix

• Citroën C3 BSI problems

• Body Control Module repair Peugeot Citroën

• Central locking not working Peugeot

• BSI reset procedure Peugeot Citroën

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