P2C78 Active Grille Air Shutter Module D Over Temperature

P2C78 is the over-temperature report of the actuator module for a fourth grille shutter D: its driver electronics have exceeded their thermal limit and the output stage has been switched off to protect it. No vehicle with a shutter D is documented, so the logic is borrowed from Ford's smart shutter actuators, which use P05C0/P05C1 for shutters A and B and set them when the controller chip reports more than 140 °C for 10 s (2023 diesel) or 30 s (2024 petrol). Typical triggers are a motor stalled against ice or a damaged linkage, a partly shorted coil, or heat soak near the radiator combined with constant repositioning. Because the protection releases once the chip cools, the code may come and go. Compared with P2C76 and P2C77 it says less about the flap than about the actuator's own health.

Likely causes

Symptoms

• Intermittent engine warning lamp
• Shutter D stops moving for a while

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: fordservicecontent.com, fordservicecontent.com, law.cornell.edu.