Description
Fuel Temperature Sensor (Heater) for Citroën and Peugeot Vehicles
Product Overview
This fuel temperature sensor with integrated heater is designed for diesel applications in Citroën and Peugeot vehicles. It provides the engine control unit with accurate fuel temperature data and the heater element helps maintain correct fuel temperature in cold conditions, improving cold starts and combustion control. The sensor is commonly identified by the part numbers 9640055680 and 1579Y6.
Features And Function
The sensor measures the temperature of the fuel and sends this information to the ECU so it can adjust injection timing, quantity and boost management for optimal combustion. The built-in heater prevents fuel from becoming too viscous or forming wax in low temperatures, ensuring reliable starting and stable idling during cold weather. Proper operation contributes to reduced emissions, smoother running and improved fuel economy.
Fitment / Compatible Models
Typical fitment (verify by part number): Citroën C5, Citroën C8, Peugeot 307, Peugeot 406, Peugeot 607, Peugeot 807. The sensor is often referenced under Stellantis/Citroën/Peugeot part numbers 9640055680 and 1579Y6.
Replacement Guide
Basic replacement steps (general guidance for experienced mechanics and competent DIYers):
- Relieve Fuel System Pressure According To The Vehicle Procedure.
- Disconnect The Battery Before Work To Prevent Short Circuits.
- Locate The Sensor — On Many PSA Diesel Engines It Is Mounted In Or Near The Fuel Filter Housing Or Fuel Line; Location May Vary By Model.
- Disconnect The Electrical Connector And Remove Any Retaining Fasteners.
- Remove The Old Sensor Carefully To Avoid Fuel Spillage Or Debris Entering The System.
- Fit The New Sensor With New Seals Or O-Rings If Supplied, Tighten To Manufacturer Torque Where Specified.
- Reconnect Electrical Connector, Repressurize The Fuel System And Check For Leaks.
- Clear Any Engine Fault Codes And Confirm Correct Operation With A Diagnostic Tool If Possible.
Installation Recommendations
- Use Genuine Or Equivalent Sealing Parts (O-Rings/Gaskets) To Prevent Leaks.
- Keep The Work Area Clean To Avoid Contaminating The Fuel System.
- After Installation, Prime The Fuel System And Check For Air In The Lines; Bleed As Required.
- Check Connector Pins For Corrosion And Ensure A Secure Electrical Connection.
- If Fault Codes Persist, Diagnose Wiring And ECU Inputs Before Replacing Additional Components.
Why This Part Fails Most Often
Common failure causes include contamination from dirty fuel or degraded filter elements, corrosion or water ingress affecting the sensor or connector, electrical faults in wiring or connectors, and mechanical damage during previous servicing. Heater element failure or internal sensor drift can lead to incorrect temperature readings, resulting in rough idling, hard starting in cold weather, increased fuel consumption or engine management fault codes.
Technical Information
- Manufacturer: Stellantis (Citroën / Peugeot)
- Model: Citroën C5; Citroën C8; Peugeot 307; Peugeot 406; Peugeot 607; Peugeot 807
- Product Codes: 9640055680
- Other Numbers: 1579Y6
Notes For Professionals
This part is commonly searched by its OEM references (9640055680, 1579Y6). For reliable diagnostics and correct post-installation checks, use a professional diagnostic tool to verify sensor readings and clear related fault codes. Always follow the vehicle manufacturer’s safety and service procedures when working on the fuel system.
