my Toyota Highlander XU70 (2020-Present) has a rough start what could be the issue

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface, and the engine is cool.
• Disconnect the negative terminal of the battery to prevent electrical shock.

2. Inspect the Battery

• Tools Required: Multimeter, wrench set
• Check the battery voltage with a multimeter; it should read around 12.6 volts when fully charged.
• Clean the battery terminals if there is corrosion present.
• Tighten any loose connections.

3. Replace Spark Plugs (if necessary)

• Tools Required: Socket set, torque wrench, spark plug socket
• Remove the ignition coil by unscrewing the retaining bolts.
• Pull the ignition coil straight out of the cylinder head.
• Use a spark plug socket to remove the spark plug.
• Install new spark plugs, ensuring they are gapped correctly according to manufacturer specifications (typically around 0.044 inches).
• Reinstall the ignition coil and torque to the manufacturer's specifications (typically around 7.2 ft-lbs).

4. Check and Replace Fuel Filter (if applicable)

• Tools Required: Fuel line disconnect tool, wrench set
• Locate the fuel filter and relieve fuel pressure by disconnecting the fuel pump fuse and running the engine until it stalls.
• Use the fuel line disconnect tool to remove the lines from the old filter.
• Install the new fuel filter, ensuring the direction of flow is correct (usually marked on the filter).
• Reconnect the fuel pump fuse and check for leaks.

5. Inspect Air Filter

• Tools Required: None (if no tools are needed)
• Remove the air filter cover and take out the air filter.
• Inspect for dirt and debris. Replace with a new air filter if dirty.

6. Reconnect Battery

• Reconnect the negative terminal of the battery.
• Start the engine to check for any improvement in the rough start condition.