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2018 Discovery Sport Rough Idle & Misfire - P0301 Code

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Brittany E. · rep 0 · May 22, 6:28 AM · 1 replies · solved · Question

Vehicle: 2018 Land Rover Discovery Sport HSE

Hey everyone,

I'm having some trouble with my 2018 Land Rover Discovery Sport HSE. Lately, it's developed a really rough idle, especially when I'm stopped at a light. It feels like the engine is shaking more than it should, and sometimes I notice a slight hesitation when accelerating from a stop.

The check engine light came on yesterday, so I hooked up my OBD scanner. It's showing a P0301 code, which points to a misfire on cylinder 1. I'm not sure if this is a simple fix like a spark plug or something more serious.

Has anyone else experienced this with their Discovery Sport or similar Land Rover models? Any advice on what I should check first before taking it to the dealer? I'm hoping to avoid a hefty diagnostic fee if it's something I can tackle myself.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 6:28 AM

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ClearTheCode admin answer:

Hello Sarah,

A P0301 code indicates a misfire detected in cylinder 1, which is consistent with your description of a rough idle and hesitation. This is a common issue that can stem from several sources within the engine and drivetrain system. Here's a breakdown of potential causes and steps you can take:

  1. Check Ignition System Components:

    • Spark Plug: The most common culprit. A worn, fouled, or damaged spark plug in cylinder 1 can cause a misfire. It's often the easiest and cheapest fix.
    • Ignition Coil: The coil pack for cylinder 1 might be failing. You can sometimes swap the coil from cylinder 1 with another cylinder (e.g., cylinder 2) and see if the misfire code moves to the new cylinder (e.g., P0302). If it does, the coil is bad.
    • Spark Plug Wire (less common on modern engines): If your specific engine uses plug wires, a damaged one could be the cause.

  2. Inspect Fuel System:

    • Fuel Injector: A clogged or faulty fuel injector for cylinder 1 can prevent proper fuel delivery, leading to a misfire. Fuel injector cleaner might help if it's a minor clog, but a faulty injector will need replacement.
    • Fuel Pressure: Low fuel pressure to the rail can affect all cylinders, but sometimes one cylinder shows symptoms first.

  3. Look for Air/Vacuum Leaks:

    • A vacuum leak near cylinder 1 could lean out the air-fuel mixture, causing a misfire. Inspect vacuum lines, intake manifold gaskets, and PCV valve/hoses for cracks or disconnections.

  4. Engine Mechanical Issues (less common but possible):

    • Low compression in cylinder 1 due to worn piston rings, valve issues, or a head gasket problem. This would require a compression test.

When to See a Shop:

  • If you've checked the spark plug and ignition coil for cylinder 1 and the problem persists.
  • If you suspect a fuel injector issue and are not comfortable replacing it yourself.
  • If you find no obvious external causes and the misfire continues, as it could indicate a more serious internal engine problem (e.g., low compression).
  • If the check engine light is flashing, this indicates a severe misfire that could damage the catalytic converter, and you should stop driving immediately and have it towed to a reputable Land Rover specialist or dealership.
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