* Coolant Temperature Sensor (CTS): This is the most common sensor and provides the engine's coolant temperature to the Engine Control Module (ECM). This sensor is usually located on the cylinder head, often near the thermostat housing. It's a fairly prominent sensor, often with a single-wire connector.
* Oil Temperature Sensor (OTS): This is less common on cars this age, but some higher trim levels or later model years might include one. It's located within the oil system, likely in the oil filter housing or oil pan.
* Intake Air Temperature Sensor (IATS): This sensor measures the temperature of the air entering the engine. It's located in the intake air system, usually somewhere near the air filter or throttle body.
To find the coolant temperature sensor (the most likely one you're looking for):
1. Consult a repair manual: A Haynes or Chilton manual specific to your Ford Fiesta's year and model is your best bet. These manuals have diagrams showing the exact location of all sensors.
2. Use a parts diagram: You can find online parts diagrams for your car using your VIN number on Ford's website or a reputable parts supplier's website. These diagrams will show the location of components, including sensors.
3. Visual inspection: With the engine cool and safe to work on, carefully inspect the cylinder head and thermostat housing area. Look for a sensor with a single-wire connector, often near coolant passages. Be cautious of hot surfaces even after the engine has cooled.
Important Note: Working on your engine can be dangerous. If you're not comfortable doing this yourself, take your car to a qualified mechanic. Incorrectly diagnosing or replacing a sensor can cause further damage.
