how to diagnose P0304 misfire code in Tesla Outback 4th Generation (2010-2014)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Tesla Outback (2010-2014). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, compression tester, fuel injector tester.
• Disconnect the vehicle's battery to ensure safety while working on electrical components.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 4:
  • Unplug the electrical connector.
  • Remove the bolt securing the ignition coil.
  • Gently pull the ignition coil out.
• Remove the spark plug:
  • Use a spark plug socket to unscrew the spark plug from the cylinder head.
• Inspect the spark plug:
  • Look for signs of wear, carbon buildup, or oil fouling.
• If damaged, replace the spark plug with the manufacturer's recommended type and torque it to the specified value (usually around 13-15 ft-lbs).

3. Check and Replace Ignition Coil

• If the ignition coil is faulty:
  • Test the coil's primary and secondary resistance with a multimeter.
  • If out of specifications, replace with a new ignition coil.
• Reinstall the new ignition coil:
  • Insert it into the cylinder, ensuring it seats correctly.
  • Secure it with the bolt and reconnect the electrical connector.

4. Verify Fuel Injector Operation

• If the injector is suspected to be faulty:
  • Use a fuel injector tester to check for proper operation.
  • Replace injector if it is not functioning correctly.
• To replace, disconnect the electrical connector and fuel line, then remove the injector from the rail.

5. Conduct Compression Test

• If the compression is low in cylinder 4:
  • Investigate further for potential internal engine issues such as a blown head gasket or valve problems.