why does my Volkswagen Passat B8 (2015-2022) have a check engine light and error code P0301?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to avoid electrical shorts.
• Allow the engine to cool down if it has been running.

2. Replace Spark Plug

• Tools Needed: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil from cylinder 1 by unscrewing the retaining bolts and gently pulling it out.
• Remove the spark plug using a spark plug socket and ratchet. Inspect the old spark plug for wear or damage.
• Install the new spark plug by hand to avoid cross-threading, then torque it to the manufacturer’s specification (typically around 22 lb-ft for VW).

3. Replace Ignition Coil

• Tools Needed: Socket set.
• Install the new ignition coil onto the spark plug, ensuring it is seated correctly.
• Reattach the electrical connector to the ignition coil and secure it with the retaining bolts.

4. Check Fuel Injector

• Tools Needed: Noid light or multimeter.
• Disconnect the fuel injector connector for cylinder 1.
• Connect a noid light to the injector harness to check for electrical pulses. If using a multimeter, measure the resistance of the injector (usually around 12-16 ohms).
• If the injector is faulty, remove and replace it with a new one.

5. Reassemble and Test

• Reconnect the negative battery terminal.
• Start the engine and allow it to idle. Monitor for any misfire symptoms or warning lights.
• Perform a test drive to ensure proper operation and check if the check engine light reappears.