In short
On Peugeot, Citroën, DS and recent Opels there's one part that defines the car's electronics: the BSI (body control module), which runs the lights, locks, wipers, power supply and part of the immobiliser. When it fails, the car does strange things or won't start, and a replacement BSI has to be cloned or configured for that vehicle (BSI cloning starts from from €100 + VAT (€121 including VAT)). For ECU remapping, the HDi and BlueHDi diesels and the PureTech petrol engines are shared between makes; before touching them we check the additive DPF and the timing belt. Workshop in Alcalá de Henares, or we come to you anywhere in the Community of Madrid (the Madrid region).
Six makes, two origins
Stellantis brings together makes that until recently were rivals. To understand their electronics it helps to separate two families:
- PSA origin: Peugeot, Citroën, DS and, in its recent models, Opel. They share platforms, the BSI and engines such as the HDi and BlueHDi diesels or the three-cylinder PureTech petrol.
- Fiat Chrysler origin: Fiat, Jeep and Alfa Romeo. MultiJet diesels, FIRE and T-Jet petrol engines, and ECUs often by Magneti Marelli as well as Bosch.
In the newest models the two families are starting to mix (there are Fiats and Jeeps with engines and platforms of PSA origin). That's why the make alone isn't enough for us: we need the model, year and engine.
The BSI: the module in charge of the body electrics
The BSI (from the French for "intelligent service box") is a control unit specific to Peugeot and Citroën, now also fitted to DS and PSA-based Opels. It acts as the hub of the body electronics:
| What it controls | What you notice when it fails |
|---|---|
| Lights, indicators and wipers | They work on their own, at the wrong time or not at all |
| Central locking and alarm | The remote fob won't unlock or the car locks itself |
| Power management and standby drain | The battery goes flat with the car parked |
| Part of the immobiliser | The car won't start even with its own key |
| Communication between modules | A string of warnings on the instrument cluster with no clear cause |
The most common causes are damp or water reaching the BSI, voltage spikes when jump-starting or changing the battery, and ageing of components on the board itself.
When it has to be replaced, a new or scrapyard BSI won't work as it is: the original's data has to be cloned, or it has to be configured (what's known as telecoding) for your vehicle and paired with the immobiliser. It's one of our services with a public price, from from €100 + VAT (€121 including VAT): you'll find it on BSI cloning.
The additive DPF, a PSA peculiarity
Many HDi and BlueHDi diesels from the PSA group use a particulate filter with additive: a small tank adds a product at every fill-up that helps burn off soot at a lower temperature. It's something most makes don't have, and it explains a lot of faults:
- When the additive runs out, the filter regenerates less effectively and blocks sooner.
- When it's topped up, the counter has to be reset with diagnostics, or the warning won't go away.
- A faulty additive pump or level sensor causes symptoms very similar to those of a full DPF.
Before thinking about the filter, we check the additive. And remember that on a road car the DPF (diesel particulate filter) isn't removed: it's diagnosed and repaired. We explain it on DPF.
PureTech: check the belt before the software
The three-cylinder PureTech petrol engine has a timing belt running in oil. On some units the belt degrades prematurely and sheds debris that can block the oil pump pick-up, leading to an oil pressure warning or worse. Before remapping a PureTech:
- We check the condition of the belt and the service history.
- We confirm the oil used is the one the manufacturer specifies.
- We read oil pressure and timing fault codes.
If the belt isn't in good shape, the first job is to replace it. More demanding software isn't what that engine needs at that point.
Gearboxes and keys
- Torque-converter automatic gearboxes (six- and eight-speed, of Aisin origin) on many recent models; single-clutch automated manuals on many earlier small cars, which feel slow and sometimes need a clutch relearn. We cover it on automatic gearboxes.
- Keys: on PSA cars the vehicle's PIN code is needed to programme them. If you don't have it, it can often be recovered by reading the modules. More on keys.
If what you're after is a remap, the general approach is on Stage 1 and the legal side on legality, ITV and insurance.
Tell us the model, the year and the symptom (or what you'd like done). If you suspect the BSI, tell us what's failing and since when.
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