how to fix P0300 code in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and materials required.
• Disconnect the battery to ensure safety while working on electrical components.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Fuel pressure gauge

2. Inspect and Replace Spark Plugs

1. Remove the engine cover (if applicable).
2. Disconnect the ignition coils from the spark plugs.
3. Use a socket wrench to remove the spark plugs.
4. Inspect the spark plugs for wear, carbon buildup, or damage.
5. Replace with new spark plugs according to manufacturer specifications (usually NGK or Denso).
6. Torque the new spark plugs to the manufacturer’s specified value (typically around 13-15 lb-ft).
7. Reconnect the ignition coils.

3. Check and Replace Ignition Coils

1. If misfires persist after replacing spark plugs, test ignition coils with a multimeter.
2. Remove any faulty ignition coils and replace them with new units.
3. Ensure the new coils are seated properly and connected.

4. Fuel System Inspection

1. Connect a fuel pressure gauge to the fuel rail.
2. Turn the ignition to the "On" position (do not start) to check fuel pressure.
3. If pressure is low, check the fuel pump and fuel filter for issues.
4. Replace the fuel filter if it shows signs of clogging.

5. Vacuum Leak Inspection

1. Start the engine and listen for hissing sounds that indicate a vacuum leak.
2. Use a smoke machine or carb cleaner around vacuum hoses and intake manifold to detect leaks.
3. Repair or replace any damaged hoses or gaskets.

6. Compression Test

1. Remove spark plugs and install a compression gauge in each cylinder.
2. Crank the engine and record the compression reading for each cylinder.
3. If readings are low, investigate further for potential internal engine issues.