how to fix P0304 misfire code on my Toyota Camry XV50 (2012-2017)

Toyota Camry XV80 (2025-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0304

3 min read

568 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 P0304 cylinder 4 misfire in Toyota Camry XV50 (2012-2017). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0304

Affected Component

Engine

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the engine to cool before performing any maintenance.

Symptoms

•Check engine light illuminated
•Rough idle or engine shaking
•Decreased fuel efficiency
•Engine stalling during acceleration
•Increased emissions

Diagnostic Steps

1
Scan the vehicle with an OBD-II scanner to confirm the P0304 code and check for additional codes.
2
Inspect the ignition system components: check the spark plug, ignition coil, and wiring for cylinder 4.
3
Perform a visual inspection of the fuel injector for cylinder 4 for signs of blockage or leakage.
4
Conduct a compression test on cylinder 4 to check for mechanical issues.
5
Check the engine for vacuum leaks that could affect cylinder 4's performance.
6
Verify the condition of the engine oil and ensure it is at the proper level.

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 gauge
•Fuel injector cleaning kit

Parts Required

•Spark plug (specific to Toyota Camry)
•Ignition coil (if necessary)
•Fuel injector (if necessary)

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Diagnostic Steps

1
Scan the vehicle with an OBD-II scanner to confirm the P0304 code and check for additional codes.
2
Inspect the ignition system components: check the spark plug, ignition coil, and wiring for cylinder 4.
3
Perform a visual inspection of the fuel injector for cylinder 4 for signs of blockage or leakage.
4
Conduct a compression test on cylinder 4 to check for mechanical issues.
5
Check the engine for vacuum leaks that could affect cylinder 4's performance.
6
Verify the condition of the engine oil and ensure it is at the proper level.

Solution

1. Preparation

Gather necessary tools and parts.
Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Spark Plug

Remove the ignition coil from cylinder 4 by unscrewing it with a socket set.
Take out the spark plug using a spark plug socket and inspect it for wear or damage.
If damaged, replace it with a new spark plug, ensuring it is gapped according to manufacturer specifications (usually around 0.044 inches for the Camry).
Reinstall the ignition coil ensuring it is seated correctly.

3. Inspect and Replace Ignition Coil (if necessary)

If the ignition coil appears damaged or faulty, remove it from the spark plug.
Disconnect the electrical connector from the ignition coil.
Install a new ignition coil and reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

Disconnect the fuel line carefully and relieve the fuel pressure.
Remove the fuel injector from cylinder 4 by unscrewing the retaining bolts.
Clean the injector using a fuel injector cleaner or replace it if malfunctioning.
Reinstall the fuel injector ensuring proper sealing.

5. Check Compression

Remove the spark plug from cylinder 4.
Insert a compression gauge into the spark plug hole and crank the engine.
Compare the compression reading to the manufacturer specifications (typically 180-200 psi); if low, further engine diagnostics may be needed.

6. Reconnect Battery and Test

Reconnect the negative battery terminal.
Start the engine and let it warm up.
Monitor for any check engine light reappearance or misfire symptoms.