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2018 Cooper S CEL - P0301 Misfire on Cylinder 1

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Ashley M. · rep 0 · May 22, 6:51 AM · 1 replies · solved · Question

Vehicle: 2018 Mini Cooper S

Hey everyone,

My 2018 Mini Cooper S (F56) just threw a Check Engine Light, and it's running pretty rough, especially at idle. I hooked up my OBD-II scanner, and it's showing a P0301 code, indicating a misfire on Cylinder 1.

The car feels a bit sluggish, and sometimes the CEL flashes, which I know means a severe misfire. I'm hoping to get some advice on what the most common culprits are for this specific code on these N/B-series engines.

What should I check first? Are there any common DIY fixes or diagnostic steps I can take before taking it to a shop? Any specific parts I should look at for a 2018 model? Thanks in advance!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 6:51 AM

0

ClearTheCode admin answer:

The P0301 code indicates a misfire detected in Cylinder 1. A flashing Check Engine Light signifies a severe misfire that could potentially damage the catalytic converter due to unburnt fuel entering the exhaust. Addressing this promptly is crucial.

Here are the common causes and diagnostic steps:

  1. Spark Plug: A worn, fouled, or damaged spark plug is a very common cause of misfires.
    • Action: Inspect the spark plug for Cylinder 1. Look for signs of oil fouling, carbon buildup, or a damaged electrode. If it looks bad, replace it.
  2. Ignition Coil: The ignition coil for Cylinder 1 might be failing.
    • Action: A common diagnostic step is to swap the ignition coil from Cylinder 1 with one from a different cylinder (e.g., Cylinder 2). Clear the codes, drive the car, and re-scan. If the misfire code changes to P0302, you've identified a faulty coil. Replace the coil.
  3. Fuel Injector: A clogged or faulty fuel injector for Cylinder 1 can prevent proper fuel delivery.
    • Action: This is harder to diagnose without specialized tools. You can try a fuel system cleaner, but if the problem persists, a professional might need to test injector pulse and spray pattern.
  4. Compression Issue: Less common, but a loss of compression in Cylinder 1 (due to valve issues, piston rings, or head gasket) will cause a misfire.
    • Action: A compression test or leak-down test performed by a mechanic can confirm this.

When to see a shop: If swapping the spark plug and ignition coil doesn't resolve the P0301 code, or if you're not comfortable performing these checks, it's best to take your Mini to a qualified mechanic. They have specialized diagnostic equipment to test fuel injectors, perform compression tests, and check for other less common issues like wiring problems or ECU faults. Continuing to drive with a severe misfire can lead to costly catalytic converter damage.

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