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Misfire Codes P0301, P0303 on 2022 A3 2.0T - Spark Plugs or Coils?

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Mike T. · rep 0 · May 25, 3:15 AM · 1 replies · solved · Question

Vehicle: 2022 Audi A3 2.0T S line

Hey everyone,

I'm reaching out for some advice regarding my 2022 Audi A3 2.0T S line. Recently, I've noticed the car running a bit rough, especially under acceleration, and the check engine light came on. I scanned it with my OBD scanner and pulled two codes: P0301 (Cylinder 1 Misfire Detected) and P0303 (Cylinder 3 Misfire Detected).

The car only has about 35,000 miles on it, so I'm wondering if it's too early for spark plugs, or if it might be an ignition coil issue. Should I just replace the spark plugs, or should I replace the coils on cylinders 1 and 3, or all of them? I'd like to tackle this myself if it's not too complicated.

Any guidance on diagnosing this further or recommended parts would be super helpful!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:15 AM

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ClearTheCode admin answer:

  1. Understanding Misfire Codes: The P0301 and P0303 codes indicate that the engine's computer has detected misfires in cylinders 1 and 3, respectively. A misfire means that a cylinder is not contributing its full power, often due to an issue with spark, fuel, or compression.

  2. Common Causes for Misfires (2.0T EA888 Gen 3/4):

    • Ignition Coils: These are very common failure points, even on relatively new vehicles. A failing coil won't deliver sufficient spark.
    • Spark Plugs: While 35,000 miles is a bit early for complete spark plug failure, worn or fouled plugs can cause misfires. The recommended interval for spark plugs on your 2.0T is typically 40,000 miles.
    • Fuel Injectors: A clogged or faulty fuel injector can prevent a cylinder from getting enough fuel.
    • Compression Issues: Less common, but low compression in a cylinder can also cause misfires.

  3. DIY Diagnostic Steps:

    • Coil Swap Test: This is the easiest first step. Swap the ignition coil from cylinder 1 to cylinder 2 (or 4), and swap the coil from cylinder 3 to cylinder 2 (or 4). Clear the codes and drive the car. If the misfire codes move to the new cylinders (e.g., P0302 and P0304), then the coils are the issue. This confirms the coils are faulty.
    • Spark Plug Swap Test: If the coil swap doesn't move the codes, you can try swapping the spark plugs in a similar fashion. If the misfire moves, the plug is faulty.

  4. Recommended Action:

    • If Coils are Suspect: Given the age and mileage, it's very plausible the coils are failing. If your diagnostic test confirms faulty coils, it's often recommended to replace all four ignition coils at once, as others may soon follow suit. Use OEM or reputable aftermarket coils (e.g., Bosch, NGK, Delphi).
    • If Plugs are Suspect: If the spark plug swap confirms a faulty plug, replace all four spark plugs. Ensure you use the correct OEM-specified spark plugs for your 2.0T engine and gap them correctly if not pre-gapped.

  5. When to See a Shop: If the misfires persist after replacing coils and plugs, or if you suspect fuel injector issues (which are more complex to diagnose and replace), it's best to take your A3 to an Audi specialist. They have advanced diagnostic tools (like VCDS) to check fuel trims, injector pulse widths, and perform compression tests to identify the root cause accurately.

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