how to fix the P0304 code on Toyota Camry XV70 (2018-2024)

Toyota Camry XV80 (2025-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0304

3 min read

534 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 XV70. 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 touching any components.

Symptoms

•Check engine light illuminated
•Rough idle, especially when the engine is cold
•Loss of power during acceleration
•Decreased fuel economy
•Engine stalling at low RPMs

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm the P0304 code and check for any other related codes.
2
Inspect the ignition coil for cylinder 4 for any visible damage or corrosion.
3
Remove the spark plug from cylinder 4 and inspect it for wear, damage, or fouling.
4
Check the wiring and connectors to the ignition coil and fuel injector for any signs of damage or corrosion.
5
Perform a compression test on cylinder 4 to determine if there are any internal engine issues.
6
If applicable, check the fuel injector operation using a noid light or a multimeter.

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
•Noid light

Parts Required

•Spark plug (for cylinder 4)
•Ignition coil (for cylinder 4)
•Fuel injector assembly (if faulty)

Related Faults

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm the P0304 code and check for any other related codes.
2
Inspect the ignition coil for cylinder 4 for any visible damage or corrosion.
3
Remove the spark plug from cylinder 4 and inspect it for wear, damage, or fouling.
4
Check the wiring and connectors to the ignition coil and fuel injector for any signs of damage or corrosion.
5
Perform a compression test on cylinder 4 to determine if there are any internal engine issues.
6
If applicable, check the fuel injector operation using a noid light or a multimeter.

Solution

1. Preparation

Gather tools and parts needed for the repair.
Disconnect the negative battery terminal to ensure safety.

2. Replace Spark Plug

Remove the spark plug from cylinder 4 using a socket and ratchet.
Inspect the spark plug gap and replace it with a new spark plug if necessary (use OEM specifications for gap).
Torque the new spark plug to the manufacturer's specification (typically around 13 ft-lbs for Toyota).

3. Inspect and Replace Ignition Coil

Unplug the electrical connector from the ignition coil for cylinder 4.
Remove the ignition coil by unscrewing the securing bolts.
Install the new ignition coil and secure it in place.
Reconnect the electrical connector to the ignition coil.

4. Inspect Fuel Injector

Remove the fuel injector connector for cylinder 4.
Check the injector for proper operation using a noid light.
If faulty, replace the fuel injector by removing it from the intake manifold and installing a new one. Ensure to use new O-rings.

5. Reassemble and Clear Codes

Reconnect the negative battery terminal.
Start the engine and allow it to run for a few minutes to ensure proper operation.
Use the OBD-II scanner to clear the error codes and check that the P0304 code does not reappear.