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2018 Discovery Sport Misfire and Rough Idle - P0301 Code

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Angela R. · 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 usual, and I've noticed a slight hesitation when accelerating from a standstill.

The check engine light came on yesterday, and I used my OBD scanner to pull the code. It's showing a P0301, which indicates a misfire in cylinder 1. I haven't done any major engine work recently, just regular oil changes and filters.

Has anyone experienced this with their Discovery Sport? What were the common culprits? I'm trying to figure out if this is something I can tackle myself or if it's definitely a trip to the dealership. Any advice would be greatly appreciated!

✓ 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 on your 2018 Land Rover Discovery Sport indicates a misfire detected in cylinder 1. This is a common issue with several potential causes, and it's good you've already pulled the code. Addressing it promptly is important to prevent further engine damage.

Here are the common causes and diagnostic steps:

  1. Ignition System Issues:

    • Spark Plug: A worn, fouled, or damaged spark plug in cylinder 1 is a very common cause. Land Rovers often require specific iridium or platinum plugs.
    • Ignition Coil: The ignition coil for cylinder 1 could be failing. This component delivers high voltage to the spark plug.
    • Spark Plug Wire (if applicable): While less common on modern engines, a faulty wire could be the culprit.

  2. Fuel System Issues:

    • Fuel Injector: A clogged, dirty, or faulty fuel injector for cylinder 1 can prevent the cylinder from getting enough fuel.
    • Fuel Pressure: Low fuel pressure to the engine overall, though less likely to cause a single-cylinder misfire, can sometimes contribute.

  3. Air/Vacuum Leaks:

    • A vacuum leak near cylinder 1 could lean out the air-fuel mixture, causing a misfire. Check for cracked hoses or loose connections around the intake manifold.

  4. Engine Mechanical Issues (Less Common but Serious):

    • Low Compression: Issues like a worn piston ring, a bent valve, or a blown head gasket can lead to low compression in cylinder 1, causing a misfire. This is usually accompanied by other symptoms like smoke from the exhaust or coolant loss.

When to See a Shop:

If you're comfortable with basic diagnostics, you can try swapping the ignition coil from cylinder 1 to another cylinder (e.g., cylinder 2). If the misfire code then moves to cylinder 2 (P0302), you've identified a faulty coil. You can do the same with spark plugs. However, if these steps don't resolve the issue, or if you suspect fuel system or mechanical problems, it's best to take your Discovery Sport to a qualified Land Rover specialist or a reputable independent mechanic. They have specialized diagnostic tools to perform:

  • Fuel pressure tests.
  • Injector flow tests.
  • Compression tests.
  • Advanced scanner diagnostics to monitor live data.

Driving with a persistent misfire can damage your catalytic converter due to unburnt fuel entering the exhaust system, leading to a much more expensive repair.

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