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How do I fix the P0128 code?

Alton Alexander
By Alton AlexanderUpdated on June 4th, 2022

P0128 is an error code that typically indicates a problem with the engine's cooling system. This code may be caused by a number of different issues, such as a faulty thermostat, a radiator leak, or a coolant sensor issue. In some cases, the code may also be caused by a problem with the engine itself.

Other common searches for this error include:

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1. Check the thermostat and make sure it is opening and closing properly

There are a few steps that need to be followed in order to check the thermostat and make sure it is opening and closing properly. The first step is to turn the ignition off and then on again to ensure that the car is in starter mode. Next, check to see if the car will turn on by pressing the gas pedal and the brake pedal at the same time. If the car will not start, then the next step is to check the fuses. The fuses are located in the trunk and can be checked by opening the hood and looking for them. If the fuses are okay, then the next step is to check the thermostat. The thermostat is located on the engine block and can be accessed by removing the spark plugs. If the thermostat is bad, then the car will not start.

2. Check the engine coolant level and make sure it is full

  1. Park the vehicle in a level area.
  2. Remove the cap on the coolant reservoir.
  3. Place a thermometer in the coolant.
  4. Compare the reading on the thermometer to the coolant level in the reservoir. If the level is too low, add coolant until the reading on the thermometer matches the level in the reservoir.
  5. Replace the cap on the coolant reservoir.

3. Check the radiator and make sure there is no debris blocking the flow of coolant

  1. Remove the front grille.
  2. Locate the radiator grille, and remove it.
  3. Look for any obstructions in the coolant flow. If you find any, remove them.
  4. Reinstall the radiator grille.
  5. Reconnect the hoses and connectors.
  6. Start the vehicle and check for any leaks.

4. Check the cooling fans and make sure they are functioning properly

  1. Check the fan speed by pressing the "D" button on the instrument panel. The fan should start up and run at a slow speed. If it does not, the fan may be defective and should be replaced.
  2. If the fan is not defective, check the connections between the fan and the engine. The fan may be incorrectly connected or the connection may be loose.
  3. Check the fan shroud and make sure it is not obstructing the fan blades.
  4. Check the fan filters and replace them if necessary.
  5. Check the cooling system hoses and replace them if necessary.

If you didn't find success with an option above, then try:

  1. Check the engine coolant temperature sensor and make sure it is functioning properly.
  2. Check the engine coolant level sensor and make sure it is functioning properly.
  3. Check for leaks in the cooling system.
  4. Take the vehicle to a mechanic to have it diagnosed and repaired.