my Toyota Highlander Fourth Generation (2020-present) has a rough idle when cold what to do

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.
• Allow the engine to cool before starting repairs.

2. Inspect and Replace Spark Plugs

• Remove the spark plug cover (if applicable).
• Use a spark plug socket and ratchet to remove the spark plugs.
• Inspect the spark plugs for signs of wear or fouling, replace with OEM specifications if necessary.
• Torque the new spark plugs to the manufacturer’s specifications (typically around 13-15 ft-lbs).

3. Clean or Replace Fuel Injectors

• If fuel injectors are clogged, use a fuel injector cleaning kit to clean them.
• If cleaning is ineffective, remove the fuel injectors using a socket and replace them with new ones.
• Ensure O-rings are properly lubricated and seated before installation.

4. Inspect and Replace the Coolant Temperature Sensor

• Locate the coolant temperature sensor, typically near the thermostat housing.
• Disconnect the electrical connector and remove the sensor using a socket.
• Install a new coolant temperature sensor and reconnect the electrical connector.
• Ensure all connections are secure.

5. Reassemble Components

• Reinstall any components removed during the inspection (e.g., spark plug cover).
• Reconnect the battery.