This interior cabin temperature sensor is designed for Citroën and Peugeot climate control systems and is commonly referenced by the part number 643618. Intended for professional workshops and competent DIYers, this sensor provides the temperature input the HVAC module uses to regulate cabin comfort. Accurate sensing helps the climate control system maintain the desired temperature, reduce compressor cycling and avoid uncomfortable temperature swings.

Key Benefits

• Direct replacement for vehicles equipped with compatible Stellantis climate control systems.
• Restores correct cabin temperature feedback to the HVAC control unit, improving climate regulation.
• Simple, cost-effective repair compared with replacing larger HVAC components.

Replacement Procedure

Access typically requires removal of interior trim or the glovebox to reach the sensor housing in the HVAC plenum or dashboard area. General steps:

• Disconnect the negative battery terminal before starting electrical work.
• Remove the appropriate trim panels or glovebox to expose the sensor location.
• Unplug the electrical connector and release any retaining clips.
• Remove the old sensor and install the new unit, ensuring correct orientation and a secure fit.
• Reconnect the connector, reassemble trim, reconnect the battery and run the climate control to verify operation.

Technical Information

• Manufacturer: Stellantis (Citroën / Peugeot)
• Model: Citroën C4 Picasso
• Product Codes: 643618
• Other Numbers: No additional reference numbers provided

Installation Recommendations

• Work In A Clean Environment: Prevent contamination of the sensor and connector during installation.
• Handle Connectors Carefully: Avoid bending or pulling wires; inspect terminals for corrosion and clean if necessary.
• Ensure Proper Seating: The sensor must sit correctly in its housing for accurate readings—do not force or misalign.
• Check HVAC Function After Fitment: Run The Climate Control Through Heating And Cooling Cycles To Confirm Correct Response.

Why The Part Most Commonly Fails

Interior temperature sensors are exposed to moisture, dust and temperature cycling inside the dashboard area. Common failure causes include connector corrosion, water ingress after windshield or HVAC work, mechanical damage during interior repairs, and age-related drift of the sensing element. When the sensor fails, symptoms typically include incorrect cabin temperature readings, unstable climate control behavior, and reduced comfort or longer run times for heating/cooling.

Notes For Mechanics And DIYers

Keep The Part Number 643618 Handy When Searching Or Ordering To Improve The Chance Of Correct Fitment. Although replacement is usually plug-and-play, always verify sensor location and connector type on the specific vehicle model and year before starting work.