This used main engine wiring harness is designed for 1.6 e-HDi petrol/diesel engines fitted to selected Citroën and Peugeot models. It restores the electrical backbone between the Engine Control Unit and essential components, ensuring reliable power distribution and signal transmission for injectors, sensors and actuators. Ideal for professional workshops and experienced DIY mechanics searching by OE number, this harness is a cost-effective way to repair electrical faults caused by damaged wiring or connectors.

Application And Fitment

Compatible With: Citroën C4, Citroën C4 Picasso, Peugeot 308 (1.6 e-HDi engine variants). Fitment must be confirmed against the vehicle’s OE part numbers listed below. The harness is intended as a direct replacement for vehicles using the corresponding Stellantis OE codes.

Technical Information

Manufacturer: Stellantis (Citroën / Peugeot)
Model: 1.6 e-HDi Engine Wiring Harness — Citroën C4 Picasso, Citroën C4, Peugeot 308
Product Codes: 9674051780, 9670855680, 9678303980
Additional Numbers: 6585L0

What The Harness Does

The main engine wiring harness routes power and data signals between the engine management system and components such as fuel injectors, pressure and temperature sensors, alternator/starter circuits, and various actuators. A correctly fitted harness ensures stable sensor readings and uninterrupted communication with the ECU, preventing misfires, limp-home modes and electrical faults.

Common Failure Modes And Frequency

Wiring harnesses do not have a fixed replacement interval. Failures typically appear after many years or high mileage, or sooner if the wiring is exposed to harsh conditions. The most common causes are connector corrosion, chafing against metal parts, heat-related insulation degradation, water ingress, mechanical damage from previous repairs or routed cable stress. Rodent damage can also be a frequent cause in parked vehicles. Symptoms include intermittent faults, injector failures, sensors reporting implausible values and engine warning lights.

Installation Recommendations

– Always disconnect the battery before beginning work to avoid short circuits and protect electronic modules.
– Carefully document or label connector locations before unplugging; take photos to ensure correct reconnection.
– Route the harness following original clips and grommets; replace any damaged clips and firewall grommets to prevent chafing and water ingress.
– Secure connectors firmly; inspect and clean mating surfaces. Use appropriate dielectric grease on exposed connector pins to reduce the risk of corrosion.
– Verify all ground straps and earth points are clean and tight.
– After installation, clear any stored fault codes and perform a functional check using an OBD diagnostic tool to confirm sensor readings and injector operation.

Why This Part Is Often Replaced

Engine wiring harnesses are subject to heat cycles, vibration and environmental exposure that progressively degrade insulation and connector integrity. Damage is often localised around engine mounts, turbocharger or exhaust regions where temperatures are highest, or where cables are pinched by previous repairs. Replacing a faulty harness is a common and effective repair to eliminate recurring electrical faults and restore reliable engine management operation.

Notes For Buyers

This is a used OEM wiring harness offered with the OE numbers shown above. Verify that one of the listed product codes matches the part being replaced on the vehicle to ensure correct fitment. Suitable for professional installation; recommended for experienced mechanics and competent DIYers familiar with engine-level electrical work.

This replacement main engine wiring harness is designed for 1.6 e-HDi Start-Stop petrol/diesel applications used across Citroën, Peugeot and DS models. It routes power and signal connections between the engine control systems, fuel injection components, start-stop equipment and vehicle electrical network. Frequently searched by original part numbers, this harness is suitable for professional garages and competent DIY mechanics who need a reliable, direct-fit wiring solution for common PSA powertrains.

Applications And Compatibility

Compatible With:

• Citroen C4 II
• Citroën C4 Picasso
• Peugeot 3008 I
• Peugeot 308
• Peugeot 5008 I

Common Search Terms: Engine Wiring Harness 1.6 e-HDI, Start-Stop Wiring Harness, 9678303980, 9674051780, 6585L0.

Technical Information

• Manufacturer: Stellantis (Citroën / Peugeot / DS)
• Model: 1.6 e-HDI Start-Stop Engine Wiring Harness
• Product Codes: 9678303980, 9674051780
• Other Numbers: 6585L0

Function And What It Controls

The Main Engine Wiring Harness Transmits Power And Signals Between The Engine Control Unit And All Engine-Related Components. Typical Connections Include Injectors, Glow Plugs (Diesel), Sensors (Crankshaft/Camshaft Position, Temperature, Pressure), Start-Stop Interface, Alternator, Starter Relay/Cut, And Various Grounds. The Harness Ensures Correct Signal Integrity And Power Distribution Required For Engine Management And Start-Stop Operation.

Why The Part Fails

Wiring Harnesses Most Often Fail Due To Mechanical Wear, Heat Damage, Vibration And Chafing Against Bodywork Or Engine Components. Additional Causes Include Corrosion Of Connector Pins, Water Ingress, Rodent Damage, And Fatigue At Bending Points Or Connector Joints. Vehicles With Start-Stop Systems Can Place Extra Cyclic Stress On Related Circuits, Increasing Likelihood Of Connector Or Wire Fatigue Over Time.

Replacement Frequency And Signs Of Failure

There Is No Fixed Interval For Replacing A Wiring Harness; Lifespan Depends On Vehicle Use, Environment And Maintenance. Typical Early Signs Of Harness Issues Include Intermittent Engine Faults, Failure To Start, Warning Lights Related To Engine Management, Loss Of Start-Stop Function, Corroded Or Loose Connectors, And Visible Damage To Insulation Or Wires.

Recommended Installation

Replacement Should Be Carried Out By A Trained Mechanic Or An Experienced DIY Enthusiast Following Manufacturer Procedures. Typical Steps:

• Disconnect The Battery And Wait A Few Minutes To Ensure Systems Are De-energized.
• Label And Photograph Connector Locations Before Disassembly To Preserve Correct Routing.
• Release Fasteners, Clips And Any Protective Conduits; Remove The Old Harness Carefully To Avoid Damaging Nearby Components.
• Route The New Harness Exactly As Original, Secure Clips And Fasteners, And Keep Wires Away From Heat Sources And Moving Parts.
• Reconnect All Plugs Firmly, Check Grounds And Protective Boots, Reconnect The Battery And Perform Basic Electrical Checks.

For Vehicles Where Reprogramming Or Adaptation Of Modules Is Required After Harness Replacement, Use Manufacturer Diagnostic Equipment. Always Follow Safety Procedures And Torque Specifications Provided By The Vehicle Manufacturer.

Why Professionals Often Prefer Original Part Numbers

Engine Wiring Harnesses Are Frequently Searched And Ordered By Original Part Number To Ensure Correct Fitment And Connector Layout. Use The Listed OE Numbers To Match The Harness To The Specific Engine Variant And Equipment Level.

Additional Notes

This Harness Is Intended As A Direct-Fit Replacement For The Listed Models And Part Numbers. When Replacing Complex Electrical Components, Take Time To Inspect Connectors, Grounds And Related Sensors; Replacing Damaged Connectors Or Renewing Protective Looms Can Prevent Recurrence Of Faults.