how to fix P0304 code in Volkswagen Golf Seventh Generation (2013-2020)

Volkswagen Golf MK7.5 (2020-Present)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0304

3 min read

547 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 Volkswagen Golf (2013-2020). 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 removing components to avoid burns.

Symptoms

•Check engine light illuminated
•Rough idle or engine shaking
•Poor acceleration
•Decreased fuel efficiency
•Engine stalling or hesitation

Diagnostic Steps

1
Scan the vehicle's OBD-II system to confirm the P0304 code and check for any related codes.
2
Inspect the ignition system components (spark plug, ignition coil) for wear or damage.
3
Check the fuel supply to cylinder 4, including fuel injector operation.
4
Perform a compression test on cylinder 4 to check for mechanical issues.
5
Inspect vacuum hoses for leaks that could affect cylinder performance.
6
Review the engine's timing and check for any timing belt or chain issues.

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 (including spark plug socket)
•Ratchet and extensions
•Compression gauge
•Torque wrench

Parts Required

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

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Diagnostic Steps

1
Scan the vehicle's OBD-II system to confirm the P0304 code and check for any related codes.
2
Inspect the ignition system components (spark plug, ignition coil) for wear or damage.
3
Check the fuel supply to cylinder 4, including fuel injector operation.
4
Perform a compression test on cylinder 4 to check for mechanical issues.
5
Inspect vacuum hoses for leaks that could affect cylinder performance.
6
Review the engine's timing and check for any timing belt or chain issues.

Solution

1. Preparation

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

2. Inspect and Replace Spark Plug

Remove the ignition coil cover if applicable.
Disconnect the ignition coil connector and unbolt the ignition coil from cylinder 4.
Remove the spark plug using a spark plug socket and ratchet.
Inspect the spark plug for wear, carbon buildup, or damage. Replace if necessary.
Install a new spark plug with a torque specification of 22 ft-lbs (30 Nm).

3. Check and Replace Ignition Coil

Inspect the ignition coil for cracks or damage.
If replacing, install a new ignition coil onto the spark plug.
Reconnect the ignition coil connector securely.

4. Inspect Fuel Injector

Remove the fuel rail cover if needed.
Disconnect the fuel injector connector for cylinder 4.
Remove the fuel injector from the rail and inspect for clogs or failure.
If necessary, replace the fuel injector and ensure it is seated properly in the intake manifold.

5. Compression Test

Remove the spark plug from cylinder 4 again.
Insert a compression gauge into the spark plug hole and crank the engine.
Record the compression reading; it should be within the manufacturer's specifications (typically around 150 psi or higher).
If compression is low, further diagnosis of mechanical components may be needed.

6. Reassemble and Test

Reinstall all components in reverse order.
Reconnect the battery terminal.
Start the engine and monitor for any check engine light reappearance.