my Cadillac Escalade T1XX (2021-Present) has a P0303 misfire code what does it mean

Symptoms

• Check engine light illuminated
• Rough idle or engine shaking
• Decreased engine power or acceleration
• Poor fuel economy
• Unusual engine noises (e.g., backfiring or popping)

Diagnostic Steps

1. Scan the vehicle's OBD-II system for stored and pending error codes.
2. Inspect the ignition system components, including spark plugs, ignition coils, and wiring for cylinder 3.
3. Check the fuel injector operation for cylinder 3 by listening for clicking sounds or performing a resistance test.
4. Perform a compression test on cylinder 3 to evaluate mechanical condition.
5. Inspect engine vacuum for leaks using a smoke machine or visual inspection.
6. Review the vehicle's maintenance history for any recent changes or repairs that may relate to the issue.

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface, the engine is off, and the ignition key is removed.
• Disconnect the negative battery terminal to prevent any electrical shorts.

2. Inspect and Replace Spark Plug

1. Remove the engine cover if applicable.
2. Remove the ignition coil from cylinder 3 by unscrewing the mounting bolts.
3. Carefully pull the ignition coil straight out from the spark plug.
4. Remove the spark plug using a spark plug socket and ratchet.
5. Inspect the spark plug for wear or damage; replace it with a new plug if necessary (refer to the owner's manual for specifications).
6. Reinstall the spark plug, ensuring it is torqued to the manufacturer's specifications (typically around 15-20 ft-lbs).
7. Reinstall the ignition coil, securing it with the mounting bolts.

3. Check and Replace Fuel Injector

1. Locate the fuel injector for cylinder 3 (consult service manual for location).
2. Disconnect the electrical connector from the fuel injector.
3. Remove any retaining clips or screws securing the injector.
4. Carefully pull the fuel injector out of the intake manifold.
5. Inspect the injector for carbon buildup or clogging. Clean or replace it as necessary.
6. Reinstall the fuel injector, ensuring it is seated properly and secured.

4. Perform Compression Test

1. Remove the ignition coil and spark plug from cylinder 3.
2. Insert the compression tester into the spark plug hole.
3. Crank the engine for several seconds to obtain a reading.
4. Compare the reading to specifications (typically 120-200 psi); replace the cylinder head gasket or perform further engine repairs if compression is low.