Description
Additional wiring harness for the START-STOP capacitor for e‑HDi engines.
Product Overview
This additional wiring harness is designed for the START‑STOP capacitor systems used on e‑HDi diesel engines. It connects the capacitor module to the vehicle electrical system, ensuring reliable energy storage and rapid power delivery during repeated engine stop/start cycles. The harness is an OE‑style replacement (OE number 9805917780) suitable for a range of Citroën and Peugeot models and is aimed at professional technicians and experienced DIY mechanics who service START‑STOP systems.
Key Features & Benefits
- Direct fit for compatible Stellantis vehicles with e‑HDi START‑STOP systems.
- Durable insulation and sealed connectors to resist engine‑bay conditions (heat, vibration, moisture).
- Restores reliable START‑STOP operation when original harness is damaged or corroded.
- OE product code referenced for fast lookup: 9805917780.
- Compatible with battery and capacitor modules used in mid‑range Stellantis diesel models.
How It Works And Typical Symptoms
The harness transmits charge and control signals between the START‑STOP capacitor (or condenser) and the vehicle electrical network. When the harness or its connectors are damaged, common symptoms include intermittent or complete loss of START‑STOP functionality, fault codes related to the energy storage module, warning lights on the dash, or poor recharge behavior of the capacitor. Replacing a faulty harness typically restores normal START‑STOP operation.
Replacement Procedure (Overview)
Recommended for trained technicians or experienced DIYers. Typical steps:
- Disconnect the negative battery terminal before any work to avoid short circuits and protect vehicle electronics.
- Locate the START‑STOP capacitor module (usually in the engine bay or near the battery area) and identify the harness routing and connectors.
- Release any retaining clips or fasteners securing the harness and carefully unplug the connectors—avoid pulling on wires.
- Fit the replacement harness in the same routing, secure with clips, and reconnect all connectors firmly.
- Reconnect the battery, start the vehicle and verify START‑STOP operation. Clear any stored fault codes with an OBD tool if necessary.
Technical Information
- Manufacturer: Stellantis (Citroën / Peugeot)
- Model(s): Citroën C4; Citroën C4 II; Citroën C4 Picasso; Citroën C4 Picasso II; Peugeot 3008 I; Peugeot 308; Peugeot 308 T9; Peugeot 5008 I
- Product Codes: 9805917780
- Other Numbers: Not listed
Installation Recommendations
Always disconnect the battery before starting work and follow the vehicle manufacturer’s safety procedures. Use proper trim and fastener tools to avoid damaging connectors and routing clips. After installation, check connector seating and secure routing to prevent chafing. If fault codes persist, perform a system scan and follow diagnostic flowcharts for the START‑STOP energy storage module.
Why This Part Fails Most Often
Common failure causes include connector corrosion from moisture ingress, broken or shorted wires due to vibration or abrasion, heat degradation of insulation, and accidental damage during other engine‑bay repairs. Rodent damage is also a possible cause in some cases. Failures usually present as intermittent faults or complete loss of START‑STOP function rather than immediate engine shutdown.
Who Should Fit This Part
This harness is suitable for professional garages and competent DIY mechanics familiar with vehicle electrics and START‑STOP systems. If diagnostics indicate harness damage or connector faults around the START‑STOP capacitor, replacing the harness is a cost‑effective repair compared with replacing the capacitor module itself.
Compatibility And Reference
Use the OE product code 9805917780 when searching for compatibility with parts catalogs and repair manuals. Models listed above are common fits for this harness; always verify connector shape and routing visually during installation.
