how to fix P0301 misfire code on Ford Mustang S550 (2015-2023)

Solution

1. Preparation

• Tools Required: OBD-II scanner, compression tester, multimeter, fuel pressure gauge, basic hand tools (socket set, wrenches).
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Ignition Components

1. Remove Engine Cover (if applicable):

   • Use a socket set to remove bolts securing the engine cover.
   • Carefully lift the cover off and set it aside.

2. Remove Spark Plug:

   • Use a spark plug socket to remove the spark plug from cylinder 1.
   • Inspect the spark plug for signs of wear or damage (e.g., carbon buildup, cracking).
   • Replace the spark plug if necessary with one that meets OEM specifications (typically Motorcraft SP-534 or equivalent).

3. Inspect and Replace Ignition Coil:

   • Disconnect the electrical connector from the ignition coil.
   • Remove the coil mounting bolt using a socket.
   • Pull the ignition coil out and inspect for damage.
   • Replace with a new ignition coil if damaged or faulty.

3. Check Fuel Injector Functionality

1. Remove Fuel Injector Connector:

   • Unplug the electrical connector from the fuel injector at cylinder 1.

2. Test Injector with Noid Light or Multimeter:

   • Connect a noid light to the fuel injector connector to check for signal.
   • If no signal is present, the engine control unit (ECU) may be faulty or there may be wiring issues.
   • If the signal is present, remove the fuel injector for inspection.

3. Inspect and Replace Fuel Injector:

   • Unclip the fuel line and pull the injector out of the rail.
   • Inspect for clogs or damage and replace if necessary with a compatible part.

4. Perform Compression Test

1. Attach Compression Tester:

   • Remove the spark plug and screw in the compression tester.

2. Crank Engine:

   • Crank the engine for a few seconds and record the reading.
   • Compare the reading to manufacturer specifications (typically 150-200 psi).
   • If compression is low, further diagnosis may be required for internal engine issues.

5. Reassemble and Test

• Reinstall the spark plug, ignition coil, and engine cover.
• Reconnect the negative battery terminal.
• Start the engine and monitor for any misfire codes.