Peugeot and Citroën BSI: what it is, common faults and repair at EcumotorStock

The Smart Service Box, better known by its initials in English (BSI), is a key electronic device that is part of the group of comfort control units for vehicles of the P.S.A. group.

Since approximately 1998, all Peugeot and Citroën vehicles began to include the BSI in all their models, in order to unify the control of several fundamental systems in their vehicles.

With the BSI, the famous multiplexed communication lines began to be used, which significantly reduced the number and cross-section of the wiring, increasing the data transmission speed between the different systems, such as switches, sensors, actuators and other control units.

One of the biggest advantages of unifying systems in a single electronic device is the ability to quickly diagnose faults in any of the components connected to the same network.

We could therefore say that the BSI is a small brain interconnected with all the other systems that make up the vehicle, and that it can also “talk” to the rest of the systems, give orders and detect operating anomalies. 

Which systems does the BSI control?

The BSI controls hundreds of fundamental aspects of the vehicle, and below we are going to name some of the most important ones.

1. Exterior and interior lights: Although it is not directly in charge of all lighting systems, it does take part in powering and managing the actuators that control them.
2. Power windows: It is directly responsible for sending the corresponding signal to the mechanisms that raise or lower the door windows. In fact, the switches of this system only act as intermediaries between human and machine, with the BSI being the one that interprets and orders the corresponding action.
3. Immobiliser: It is responsible for storing part of the data that allows the engine to start. It holds the data of the ignition keys and the remote control (opening and closing of doors).
4. Mileage: The total mileage data of the vehicle is stored in its memory and shared with the instrument cluster.
5. Vehicle identification: It stores all the identifying data of the vehicle, such as the V.I.N., body type, engine and equipment.
6. Windscreen/rear window wipers:  It is responsible for sending the signals needed to operate the windscreen/rear window wipers.
7. Door locking: It receives the door opening and/or closing signals, interprets them and sends the corresponding signal to the locks.
8. Climate control: Depending on the type of climate control system the vehicle has, the role of the BSI will be more or less important, but either way, its involvement is essential.
9. Sound system: It stores the information of the vehicle's sound system or multimedia system to prevent possible theft.
10. Electrical power management: It is part of the system that manages the electrical power coming from the battery. If you know the message (Energy saving mode) it means the BSI has switched off the main consumers to avoid a total loss of electrical power.
11. Passive safety systems: The BSI sends and receives information from the passive safety elements, including the restraint system (AIRBAG). 

BSI coding (the same one works for many different models)

Although there are hundreds of different references, the same type of BSI can be found in very different vehicles with very different equipment,

This means that a BSI with a different reference but sharing the same “family” can be configured for dozens of different models of the PSA group.

However, it is not possible to swap the BSI from one vehicle to another, even if they are identical, since each one has certain parameters that are unique to each vehicle.

To adapt the BSI to a specific vehicle, a configuration process is required that must only be carried out by qualified personnel with professional tools, otherwise we could cause very serious faults in the vehicle's electrical and electronic systems. 

Typical BSI faults

The BSI is exposed to a large number of faults because of its interconnection with the rest of the vehicle's systems.

As a result, certain anomalies such as voltage spikes, short circuits, or tampering by inexperienced hands with the vehicle's different elements, can cause partial or total destruction of the unit.

Faults caused by a faulty BSI

As we have said, the BSI is interconnected with dozens of vehicle systems, so the malfunction of some of these systems may come from the BSI itself.

I wanted to make a short list of the most common faults for which a BSI needs to be repaired or replaced, so that you can get an idea in case your vehicle has any of these faults.

1. The engine does not start.
2. Power windows and/or locks malfunctioning.
3. One or more lights do not work.
4. The instrument cluster is off or has all the warning lights permanently on.
5. Windscreen/rear window wipers cannot be controlled.
6. Faults in the A/C system and/or automatic climate control.
7. Battery charging anomalies.
8. Start/stop disabled.
9. Electronic anti-theft always active.
10. Anomaly in parking sensors, light sensor, rain sensor, etc.

Behaviours that most often cause BSI faults

Most BSI faults are caused by age or by the failure of other vehicle systems. However, a high percentage of faults are caused by a lack of maintenance or by tampering with the electrical system and/or the vehicle's components.

A typical example that causes BSI faults is moisture getting in, sometimes because of blocked drains that channel water to the outside, or because the interior of the vehicle is cleaned with too much water or liquid products.

Another example is the installation of gadgets, such as sound equipment, multimedia equipment, additional lights, etc.

This type of installation must be carried out by experienced people and always using approved quality products, although our recommendation is not to tamper with them under any circumstances. 

The biggest problem is the lack of stock

If you own a PSA group vehicle that is more than 10 years old, it is very likely that even the official service can no longer solve a BSI fault for you. It is very common that after those years there is no longer stock of this type of part.

Obviously the official service is not going to repair an electronic component of this kind, so the solution is to go to a specialist.

 How do we fix BSI faults at EcumotorStock?

At EcumotorStock we are specialists in the repair and/or coding of control units and we are able to diagnose, repair or replace BSIs.

Whether you bring your vehicle to our premises or send it to us from anywhere in the world, we will carry out a diagnosis and give you the best option to solve the problem.

It does not matter whether you are a professional or a private customer, you will be served with the same guarantees.

With more than 15 years of experience in the sector, more than 10,000 control units in stock and a team of highly qualified professionals, you can rest easy, knowing you will be in good hands.

You only need to visit us at our premises or get in touch through our usual channels. (SOCIAL MEDIA LINKS, WHATSAPP PHONE NUMBER)