Repair of the 48V high-voltage battery and power wiring in a Peugeot 5008 MHEV

Fixing the Consequences of a Systemic “Flaw” in Stellantis’ Hybrid Platforms: The Peugeot 5008 Case

A 2024 Peugeot 5008 crossover with only 32,071 km on the odometer was brought to the STS.Electro workshop with a critical malfunction in its 48-volt mild hybrid (MHEV) system.

This vehicle is built on the shared Stellantis architecture, which it shares with related models (notably the Citroën DS7). STS.Electro’s service experience shows that problems with 48V batteries in these cars are systemic in nature and are related to two main factors:

1. Vulnerable battery location: The battery is installed at the lowest point of the body—under the car’s underbody. Despite the presence of a metal protective shield, hitting a high local obstacle (a rock, curb, or ice hump) can easily cause deformation of the battery case, damage to internal components, or disruption of the liquid cooling system, creating a risk of a short circuit and even a fire.
2. Design issue with the power wiring: The main defect is the systematic burning out of the 48V power wires. Due to a poor factory connection at the joint or an incorrectly calculated conductor cross-section, critical overheating occurs under constant load. The protective insulation and the plastic terminal entry on the battery case begin to melt, after which the wire simply burns out.

In-depth diagnostics and the STS.Electro engineering approach

During the initial inspection and fault diagnosis of the vehicle, STS.Electro specialists identified that the 48V power cable terminal had completely burned out, with thermal damage to the outer plastic housing of the terminal block on the battery itself.

Scanning the systems with the Autel MaxiSys MS909&EV diagnostic system revealed a whole cascade of errors triggered by a voltage drop and an open circuit in the 48V power circuit:

• P0AE3:09 in the traction battery module (TBMU_MHEV) – critical failure of the internal power contactor circuit for the traction battery precharge due to a physical break in the line.
• P0562 / P056216 in the ESP and power steering (DAE) modules—insufficient power supply error (low voltage in the vehicle electrical system).
• U1146:87 – Loss of communication with the electric/hybrid transmission control ECU via the high-speed CAN bus.

Diagnostic and identification data for the damaged VEB component:

• Module manufacturer: FinDreams Battery (a BYD subsidiary), model PEV7901.
• OEM part number (PSA / Stellantis): 9863828580
• Assembly number: 9863571180 | Software (SW): 9697370280
• Technical specifications: Li-Ion NCM (C58MSA), 43.8 V, 20 Ah, 876 Wh (0.876 kWh), weight 12.1 kg.

Since the plastic VVB entry point had completely burned through, it was no longer possible to safely operate the original housing. However, replacing the entire power wiring harness (as required by the manufacturer) was completely impractical.

Scope of Work Performed

STS.Electro specialists carried out a comprehensive set of procedures to safely restore the 48V power circuit and replace the damaged components:

• Dismantling and inspection: The 48V circuit was de-energized, the battery was removed, and the damage was assessed: burn marks on the conductors, charred insulation, and a complete burn-through of the plastic VBB entry were documented.
• Cable preparation: We cut away the damaged section down to bare copper, removed the overheated insulation, and treated the conductors with a protective anti-corrosion compound.
• High-pressure crimping: The cable was extended using a solid crimp sleeve with an enlarged cross-section, crimped deeply using hydraulic pressure to minimize contact resistance.
• Multi-layer insulation: The joint was sealed with thick-walled heat-shrink tubing featuring an adhesive layer for moisture protection and covered with an additional heat-resistant sleeve.
• Battery Replacement: We installed a pre-inspected, used 48V FinDreams/BYD battery (OEM: 9863828580) that had previously passed an incoming inspection.
• Adaptation and Testing: We programmed and paired the new battery pack with the BMS, cleared any errors, and tested the system under load.

Thanks to this targeted repair, the power circuit has been restored to factory reliability standards without the need for a costly replacement of the entire wiring harness.

The Peugeot 5008 has been fully restored and returned to normal operating condition. Thanks to targeted engineering repairs on the power cable, we were able to eliminate the systemic “contact issue” and get the car back on the road without incurring unnecessary expenses for a new power cable.

Looking for professional service for your electric vehicle or hybrid?

Is your official dealer insisting on a costly replacement of the entire high-voltage battery or the entire wiring harness? Don’t rush into overpaying.

The STS.Electro team specializes in in-depth engineering diagnostics and high-quality on-site repairs of complex components. We maintain our own inventory of proven components, provide a warranty on all work performed, and find optimal technical solutions for both private owners and automotive businesses.

Contact our specialists today for a consultation and to schedule a diagnostic check!