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.
2012 Smart ForTwo Coupe (451.331) L3-1.0L (132.910)FACTORY OEM SERVICE PROCEDURE
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
GF07.04-P-6040MCC Coolant Temperature Sensor, Component Description
B11/4 Coolant temperature sensor
Location
The coolant temperature sensor is screwed onto the left side on the cylinder head.
Task
The coolant temperature sensor detects the coolant temperature and transmits a corresponding voltage signal to the ME-SFI [ME] control unit (N3/10).
Function
The NTC resistor integrated within the coolant temperature sensor changes its electrical resistance according to the coolant temperature. The ME-SFI [ME] control unit applies a sensor voltage of 5 V to pin 1 (1) and evaluates signal voltage at pin 2 (2) according to the coolant temperature.
Factory Service Tools
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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.