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Rough Idle and CEL on 2020 Countryman All4 - Spark Plugs?

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Mike T. · rep 0 · May 25, 5:00 AM · 1 replies · solved · Question

Vehicle: 2020 Mini Countryman All4

Hi everyone,

I'm experiencing some issues with my 2020 Mini Countryman All4. Lately, it's developed a pretty rough idle, especially when I first start it up in the morning. It feels like it's sputtering a bit. The Check Engine Light also came on a few days ago.

I've heard that rough idles and CELs can sometimes be related to spark plugs or ignition coils. My Mini has about 45,000 miles on it. Could it be time for new spark plugs? What else should I be checking? Any advice on diagnosing this would be great!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 5:00 AM

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ClearTheCode admin answer:

A rough idle combined with a Check Engine Light (CEL) on your 2020 Mini Countryman All4 at 45,000 miles definitely points towards an ignition system issue, and spark plugs are a very common culprit.

  1. Common Causes:

    • Worn Spark Plugs: Over time, spark plugs degrade, leading to inconsistent spark and misfires. Mini recommends spark plug replacement typically between 30,000 to 60,000 miles, depending on the engine and driving conditions. Your mileage puts you in the range where they could be due.
    • Failing Ignition Coils: Ignition coils provide the high voltage to the spark plugs. A failing coil can cause a misfire on a specific cylinder.
    • Fuel System Issues: Clogged fuel injectors or a failing fuel pump can also cause rough running.
    • Vacuum Leaks: Leaks in the intake system can lead to unmetered air entering the engine, causing a lean condition and rough idle.

  2. Diagnostics: The first step is to get the CEL codes read. Most auto parts stores will do this for free. Look for codes like:

    • P0300: Random/Multiple Cylinder Misfire Detected
    • P0301-P0304 (or higher): Misfire Detected Cylinder 1-4 (or specific cylinder number) These codes strongly indicate an ignition problem.

  3. DIY Steps (if P030X codes are present):

    • Inspect Spark Plugs: If you're comfortable, remove the spark plugs (one at a time to avoid mixing coils/plugs) and inspect their condition. Look for signs of wear, oil fouling, or unusual deposits.
    • Swap Ignition Coils: If you have a P030X code for a specific cylinder, you can try swapping that cylinder's ignition coil with one from a non-misfiring cylinder. If the misfire code follows the coil, you've found the issue.

  4. When to See a Shop:

    • If you're not comfortable performing the diagnostic steps or replacing components yourself.
    • If the CEL codes are not P030X, indicating a different underlying problem.
    • If replacing spark plugs and/or coils doesn't resolve the issue, as it could point to more complex problems like fuel delivery, compression issues, or a deeper electrical fault.
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