Cadillac Error Code P0303: How to Fix It

Q: What causes P0303 code in Cadillac vehicles?

Common causes include faulty spark plugs, bad ignition coils, clogged fuel injectors, vacuum leaks, low compression due to worn piston rings or valves, or carbon buildup in the combustion chamber.

Q: Can I drive my Cadillac with P0303 code?

You should avoid driving with this code as it can cause catalytic converter damage, reduced fuel economy, and potential engine damage. If you must drive, do so gently and get it repaired as soon as possible.

Q: How much does it cost to fix P0303 on a Cadillac?

Costs vary depending on the cause. Spark plug replacement costs $100-200, ignition coils $150-400 each, fuel injectors $300-800, and internal engine repairs can cost $1,500 or more.

Q: Will P0303 clear itself after fixing the problem?

The code may clear itself after several drive cycles if the problem is fixed, but it's best to use an OBD2 scanner to clear it immediately after repairs to verify the fix worked.

Q: How do I know if it's the spark plug or ignition coil causing P0303?

Swap the coil and spark plug from cylinder 3 with another cylinder. If the misfire moves to the new cylinder, you've identified the faulty part. If it stays on cylinder 3, the problem is likely compression-related or with the fuel injector.

Abstract

The P0303 error code indicates that your Cadillac's engine control module has detected a misfire in cylinder 3. This can cause rough idling, reduced power, poor fuel economy, and potential engine damage if not addressed promptly.