Description
Sensor for intensity of solar radiation with cover for Citroën and Peugeot vehicles.
This sun radiation sensor (sun load sensor) monitors the intensity of incoming sunlight and communicates with the vehicle’s climate control to help maintain stable cabin temperature and comfort. Supplied with protective cover and referenced under part numbers 643604 and 643676, this unit is a direct-fit replacement for affected Citroën and Peugeot models.
Application And Function
The sensor is used by automatic HVAC systems to measure sun load and to adjust blower speed, blend doors and temperature regulation accordingly. Typical fitment includes Citroën C8 and Peugeot 807 models that share the same climate control strategy. Common search terms: sun sensor, sun load sensor, solar radiation sensor, climate control sensor, 643604, 643676.
Installation Recommendations
Location: Usually mounted on the upper dashboard near the base of the windshield, often under a small cosmetic cover. Replacement steps (general guidance):
- Remove the dashboard trim or cover that hides the sensor while taking care not to damage clips.
- Disconnect the electrical connector and unplug the sensor.
- Remove any retaining screws or clips and replace the sensor with the new unit, including the supplied cover.
- Reconnect the connector, reassemble trim and verify proper seating of the cover to avoid light leakage or shading of the sensor.
- After installation, check the automatic climate control operation. If the HVAC control stores fault codes, clear them and verify normal function.
Why This Part Commonly Fails
Sun sensors are exposed to constant UV radiation, heat cycles and temperature extremes behind the windshield. Common failure causes include gradual degradation of the sensor element (photodiode), plastic cover yellowing or cracking, contamination by dust or adhesives, moisture ingress, or connector corrosion. Failures typically present as incorrect cabin temperature regulation, uneven climate behavior under sunny conditions, or HVAC error traces related to the sun sensor.
Technical Information
- Manufacturer: Citroën / Peugeot (Stellantis)
- Model: Citroën C8; Peugeot 807
- Product Codes: 643604, 643676
- Other Numbers: 643604/643676, 643676, 643604
Notes for Fitment: This item is supplied as a direct replacement sun radiation sensor with cover. Ensure the sensor’s mounting position and connector match the vehicle harness before final installation. Proper seating of the cover and correct alignment toward the windshield are important for accurate readings.
