Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fan Speed Sensor (FSS)
The FSS is a Hall effect sensor integral to the visctronic drive fan (VDF). The PCM monitors the sensor input and controls the VDF speed based upon the engine coolant temperature, the transmission fluid temperature, and the intake air temperature (IAT) requirements. When an increase in fan speed for vehicle cooling is requested, the PCM monitors the FSS signal and outputs the required PWM signal to a fluid port valve within the VDF.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.