my Toyota Highlander XU70 (2020-Present) has a hard time starting when it's cold

Solution

1. Preparation

• Gather tools and parts. Ensure the vehicle is parked on a level surface and the engine is cool.
• Tools Required: OBD-II scanner, multimeter, fuel pressure gauge, socket set, torque wrench, basic hand tools.
• Safety Warnings: Disconnect the battery before working on electrical systems.

2. Battery Inspection and Replacement

• Sub-steps:
  1. Use a multimeter to measure battery voltage.
  2. If the voltage is below 12.4V, remove the battery using a socket set.
  3. Replace the battery with a new one if it’s faulty, ensuring proper terminal connections.
  4. Torque the battery terminals to 5-7 ft-lbs.

3. Spark Plug Inspection and Replacement

• Sub-steps:
  1. Remove the engine cover using a socket set to access spark plugs.
  2. Inspect each spark plug for wear, cracks, or carbon buildup.
  3. Replace any faulty spark plugs with OEM specifications (typically NGK or Denso for Toyota).
  4. Torque the new spark plugs to 13-15 ft-lbs.

4. Fuel System Check

• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the 'ON' position without starting the engine to check for pressure; it should be within specifications (usually around 50-60 psi).
  3. If pressure is low, inspect the fuel pump and filter, replacing them if necessary.
  4. Reconnect any fuel lines securely.

5. Coolant Temperature Sensor Inspection

• Sub-steps:
  1. Locate the engine coolant temperature sensor (usually near the thermostat housing).
  2. Disconnect the sensor and test it using a multimeter.
  3. Replace the sensor if readings are outside specifications.
  4. Reconnect the sensor and ensure all connections are secure.