how to fix P0303 code in Toyota Highlander Third Generation (2014-2019)

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0303

3 min read

575 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0303 cylinder 3 misfire in Toyota Highlander (2014-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0303

Affected Component

Engine

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Relieve fuel system pressure before removing fuel components.

Symptoms

•Check engine light illuminated
•Rough idle
•Loss of power during acceleration
•Decreased fuel efficiency
•Engine stalling or hesitation

Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to confirm the P0303 code.
2
Inspect the ignition system components (spark plug, ignition coil) for signs of wear or damage.
3
Check the fuel injector for cylinder 3 to ensure it is functioning properly.
4
Perform a compression test on cylinder 3 to assess engine health.
5
Examine vacuum hoses for leaks that might affect the cylinder's performance.
6
Inspect the engine's wiring and connectors related to the ignition system and fuel injector.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Socket set
•Torque wrench
•Compression tester
•Multimeter

Parts Required

•Spark plug
•Ignition coil for cylinder 3
•Fuel injector for cylinder 3 (if needed)

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to confirm the P0303 code.
2
Inspect the ignition system components (spark plug, ignition coil) for signs of wear or damage.
3
Check the fuel injector for cylinder 3 to ensure it is functioning properly.
4
Perform a compression test on cylinder 3 to assess engine health.
5
Examine vacuum hoses for leaks that might affect the cylinder's performance.
6
Inspect the engine's wiring and connectors related to the ignition system and fuel injector.

Solution

1. Preparation

Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter.
Safety Warnings: Disconnect the battery before working on electrical systems.

2. Replace Spark Plug and Ignition Coil

Remove Engine Cover (if applicable).
- Use a socket set to remove bolts securing the engine cover.
Remove Ignition Coil for cylinder 3.
- Disconnect the electrical connector from the ignition coil.
- Unscrew the bolts holding the ignition coil in place and remove it.
Replace Spark Plug in cylinder 3.
- Use a spark plug socket to unscrew the old spark plug.
- Check the gap on the new spark plug and adjust if necessary.
- Install the new spark plug and torque it to 13 lb-ft (18 Nm).
Install New Ignition Coil.
- Position the new ignition coil over the spark plug and secure it with bolts.
- Reconnect the electrical connector.

3. Check and Replace Fuel Injector (if necessary)

Remove Fuel Rail.
- Relieve fuel pressure by removing the fuel pump fuse and running the engine until it stalls.
- Disconnect fuel lines and unbolt the fuel rail.
Replace Injector for Cylinder 3.
- Remove the old fuel injector from the fuel rail.
- Install the new injector and ensure it seats properly.
Reinstall Fuel Rail and reconnect fuel lines.

4. Perform Compression Test

Remove Spark Plug from cylinder 3 again.
Insert Compression Tester into the spark plug hole.
Crank the Engine and record the compression reading.
- Ensure the reading is within the manufacturer’s specified range (usually around 150-200 psi).
Reinstall Spark Plug and ignition coil after testing.