my Toyota Highlander XU70 (2020-Present) has a check engine light with code P0303, what does it mean...

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Spark Plug

• Remove the engine cover if necessary.
• Locate and remove the spark plug for cylinder 3 using a socket wrench.
• Inspect the spark plug for wear, carbon buildup, or damage.
• Replace the spark plug with a new one that meets OEM specifications (typically NGK or Denso for Toyota).
• Torque the new spark plug to the manufacturer's specifications (usually around 13 lb-ft).

3. Check and Replace Ignition Coil

• Unplug the electrical connector from the ignition coil for cylinder 3.
• Remove the ignition coil using a socket or wrench.
• Inspect the ignition coil for damage or corrosion.
• Replace with a new ignition coil that meets OEM specifications.
• Reconnect the ignition coil electrical connector.

4. Test Fuel Injector

• Remove the fuel injector from cylinder 3 using appropriate tools.
• Inspect for clogs or damage, and clean or replace the fuel injector if necessary.
• Reinstall the fuel injector and ensure proper seating and connection.

5. Perform Compression Test

• Remove the spark plugs from all cylinders.
• Insert a compression tester into cylinder 3 and crank the engine.
• Record the compression reading and compare it to the manufacturer's specifications (typically around 180-200 psi).
• If compression is low, further investigation is required, potentially leading to valve or piston issues.

6. Reassemble and Clear Codes

• Reinstall all components removed during the repair process.
• Reconnect the battery.
• Use the OBD-II scanner to clear the check engine light and stored codes.