my Volkswagen Golf MK7 (2015-2019) has a temperature gauge that fluctuates

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, coolant pressure tester, and basic hand tools.
• Ensure the vehicle is parked on a level surface, and the engine is cool before starting work.

2. Replace Engine Coolant Temperature Sensor

• Sub-steps:
  1. Disconnect the battery's negative terminal to avoid electrical shorts.
  2. Locate the engine coolant temperature sensor (usually near the thermostat housing).
  3. Disconnect the electrical connector from the temperature sensor.
  4. Use a socket set to remove the sensor from the engine block.
  5. Apply thread sealant (if required) to the new sensor and install it into the engine block, tightening to the manufacturer's specified torque (typically around 15 Nm).
  6. Reconnect the electrical connector to the new sensor.

3. Inspect and Replace Thermostat (if necessary)

• Sub-steps:
  1. Drain the engine coolant using a coolant pressure tester or by removing the drain plug.
  2. Remove any components obstructing access to the thermostat (e.g., intake manifold).
  3. Unscrew and remove the thermostat housing.
  4. Remove the old thermostat and replace it with a new one, ensuring the correct orientation.
  5. Reinstall the thermostat housing and tighten to the specified torque (typically around 20 Nm).
  6. Refill the cooling system with the appropriate coolant mixture.

4. Check for Coolant Leaks

• Sub-steps:
  1. Reconnect the battery's negative terminal.
  2. Start the engine and allow it to reach operating temperature while monitoring for leaks around the sensor and thermostat.
  3. If leaks are present, recheck connections and tighten as necessary.