how to fix a P0128 code on my Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Replace the Thermostat

• Tools Required: Socket set, torque wrench, gasket scraper, new thermostat, new gasket, coolant.
• Sub-steps:
  1. Drain the coolant from the radiator using a drain pan.
  2. Remove the radiator cap to allow for draining.
  3. Locate the thermostat housing, typically near the engine block.
  4. Unbolt the thermostat housing using a socket set, and gently remove it.
  5. Take out the old thermostat and gasket. Clean the mating surfaces with a gasket scraper.
  6. Install the new thermostat and gasket, ensuring it is seated properly.
  7. Reattach the thermostat housing and torque the bolts to the manufacturer's specifications (typically around 15-20 ft-lbs).
  8. Refill the cooling system with the appropriate coolant mixture.

3. Replace the Coolant Temperature Sensor (if necessary)

• Tools Required: Socket set, new coolant temperature sensor.
• Sub-steps:
  1. Locate the coolant temperature sensor, which is usually near the thermostat or engine block.
  2. Disconnect the electrical connector from the sensor.
  3. Unscrew the sensor using a socket set.
  4. Install the new sensor and reconnect the electrical connector.

4. Reconnect Battery

• Reconnect the negative battery terminal securely.