If your Citroën C4, DS4, DS5 or Peugeot 508 shows a "Battery charge fault" warning, won't start, or drains its battery overnight, the BPGA (battery protection and management unit) in the engine-bay fuse box is a common cause.
Rule out the battery and alternator first, then compare the part number on your unit (often 9665878080) before ordering a replacement.
It's one of the most frustrating faults on modern Peugeot, Citroën and DS cars: the dashboard tells you the battery isn't charging, yet the battery and alternator test fine. In many cases the culprit is a part most drivers have never heard of. This guide explains what the BPGA does, the symptoms it causes, how to tell it apart from a battery or alternator fault, and how to find the correct replacement.
What Is the BPGA (and Why Is It Called a BSM)?
BPGA is PSA's name for the battery protection and power management unit. On models such as the Citroën C4 (second generation), DS4, DS5 and Peugeot 508, it is built into the fuse box under the bonnet, next to the battery. That's why you'll also see it described as the engine fuse box or BSM fuse box, and why parts sellers list it as a "battery protection management unit fuse box".
Inside the unit is a heavy-duty relay that connects and disconnects the main battery supply to parts of the car's electrical system. It also works with the stop/start system and the battery monitoring sensor to manage how power is shared. When that relay or its control circuit fails, the car's electronics can no longer trust the power supply, and warnings start appearing.
🔎 Good to know: the relay inside the BPGA is sealed, so it can't normally be repaired or replaced on its own. When it fails, the usual fix is to replace the complete unit.
Symptoms of a Failing BPGA
BPGA faults often start as intermittent warnings that come and go, then become permanent. Look out for:
- "Battery charge fault" on the dashboard, sometimes with the service light or a "stop the vehicle" type message.
- No-start or no-crank, even though the battery is charged.
- Battery draining overnight while the car is parked, with no obvious cause.
- Stop/start stops working or behaves erratically.
- Intermittent electrical cuts, such as accessories switching off or behaving oddly.
- Problems appearing after a battery change or jump-start.
A diagnostic scan often points straight at it. A typical fault reads along the lines of "Supplies protection and management unit: central power switch positive relay status fault", sometimes logged as B1624.
Why BPGA Units Fail
Relay sticking
The internal relay can stick closed or open. If it sticks closed, the system can't isolate circuits and may drain the battery.
Battery work
Voltage spikes from a jump-start, a badly connected battery or reversed leads can damage the unit's electronics.
Heat & age
It sits in the engine bay, so years of heat cycles and vibration take their toll on the relay and solder joints.
Moisture & corrosion
Water getting into the fuse box or its connectors can cause corrosion and intermittent faults.
BPGA, Battery or Alternator? How to Tell
The "battery charge fault" warning doesn't always mean the BPGA has failed. Ruling out the cheaper, more common causes first saves money and avoids ordering a part you don't need.
| What you notice | Most likely cause | What to check |
|---|---|---|
| Slow cranking, battery won't hold charge after a full charge | Worn battery | Have the battery load-tested |
| Charging voltage low with engine running, warning while driving | Alternator or drive belt | Measure voltage at the battery with the engine running |
| Battery and alternator test fine, but the warning stays on | BPGA | Read fault codes for a relay or supply-management fault |
| Battery drains overnight, no other faults | BPGA relay stuck, or another parasitic drain | Parasitic drain test; check BPGA fault codes |
| Faults started straight after a new battery or jump-start | BPGA damage, or battery sensor not set up | Check codes and that the new battery is configured correctly |
💡 Tip: if you've just fitted a new battery, check the terminals and battery sensor connection are tight and correct before condemning the BPGA. A loose or misfitted connection can trigger similar warnings.
Which Part Number Does My Car Need?
Peugeot, Citroën and DS use different BPGA units depending on the model, so matching the part number matters. D2P Autoparts stocks two of the most common:
Engine-bay fuse box with BPGA
Listed for selected Citroën C4 (II), C4 Cactus, DS4, DS5, DS 4 / DS 4 Crossback, DS 5, Peugeot 508 and 508 SW. Check your exact engine and year on the product page.
Battery management protection unit
For Citroën C4 Picasso, Grand Picasso, Dispatch and Peugeot 3008, 308 and 5008 diesels.
How to confirm yours
- Find the label on your existing unit – open the bonnet and look for the part number printed on the fuse box or BPGA housing.
- Compare it with the OE numbers listed on the product page. Several numbers can apply to the same part.
- Check your model, engine and year with our reg plate search or the Make, Model & Year checker.
- Still unsure? Call us with your reg or VIN and we'll confirm it for you.
Replacing the BPGA: DIY or Garage?
Replacing the unit is mostly a matter of unplugging and transferring connections, so it's within reach of a confident DIYer. Because it handles the car's main power supply, care matters:
- Disconnect the battery before starting and wait for the system to power down.
- Photograph every connector and the fuse layout before removing anything.
- Transfer fuses carefully into the same positions on the new unit.
- Tighten power connections properly – a loose main feed can cause new faults.
- Read and clear fault codes after fitting, then test stop/start and charging.
⚠️ Configuration: on some models (later C4 and DS4 in particular), the engine fuse box may need to be set up with a diagnostic tool after replacement. If you don't have one, a garage or auto electrician with PSA diagnostics can do this.
Not Sure It's the BPGA? Talk to a Real Parts Expert
Electrical faults are easy to misdiagnose, and this isn't a cheap part to get wrong. Call our team with your registration or VIN and the warning you're seeing. We'll help you confirm the right part number before you order – a real person, not a chatbot.
Mon–Fri 8am–5pm · Sat 8am–12pm (UK time)
Frequently Asked Questions
What does "battery charge fault" mean on a Peugeot or Citroën?
It means the car's power management has detected a problem with charging or supply. The cause can be the battery, the alternator, wiring, or the BPGA unit in the engine fuse box. Testing the battery and alternator first helps narrow it down.
Can a faulty BPGA drain my battery?
Yes. If the internal relay sticks, circuits that should switch off when the car is parked can stay powered, which can flatten the battery overnight.
Can the BPGA be repaired?
The relay inside is sealed, so the usual fix is to replace the complete unit rather than repair it.
Does a new BPGA need coding?
It depends on the model. Some owners fit it as a direct swap, while some later C4 and DS4 models may need the engine fuse box set up with a diagnostic tool. Check with a garage that has PSA diagnostics if you're unsure.
Is 9665878080 the same as 9675349880?
No. 9665878080 is listed for selected C4, DS4, DS5 and 508 models, while 9675349880 is for C4 Picasso, Grand Picasso, Dispatch, 3008, 308 and 5008. Always compare the number on your existing unit.
Can I still drive with a battery charge fault warning?
It isn't advisable. If the car isn't charging or managing power properly, it could stop or fail to restart. Get it checked as soon as possible.
