my Toyota Highlander XU70 (2020-Present) has a rough idle when cold what's the fix

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Clean the Throttle Body

• Remove the air intake duct connected to the throttle body.
• Use throttle body cleaner and a soft cloth to clean the interior of the throttle body.
• Ensure the throttle plate moves freely without obstruction.
• Reattach the air intake duct securely.

3. Replace Spark Plugs

• Remove the ignition coils from the spark plugs by unbolting and disconnecting electrical connectors.
• Use a spark plug socket to remove and inspect the old spark plugs for wear.
• Install new spark plugs, ensuring they are gapped to manufacturer specifications (typically around 0.043 inches).
• Reinstall the ignition coils and ensure they are secure.

4. Check and Replace Engine Coolant Temperature Sensor (if necessary)

• Locate the engine coolant temperature sensor, typically near the thermostat housing.
• Disconnect the electrical connector and remove the sensor using a socket wrench.
• Install the new sensor with a new O-ring to prevent leaks.
• Reconnect the electrical connector.

5. Final Checks

• Reconnect the vehicle battery.
• Start the engine and allow it to idle until it reaches normal operating temperature.
• Monitor the idle quality and check for any new error codes using the OBD-II scanner.