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2020 Mirage G4 Rough Idle & P0301 Misfire Code

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Sarah K. · rep 0 · May 25, 4:05 AM · 1 replies · solved · Question

Vehicle: 2020 Mitsubishi Mirage G4 ES

My 2020 Mitsubishi Mirage G4, with about 40,000 miles, has suddenly started running really rough, especially at idle. It feels like it's going to stall sometimes. The Check Engine Light came on and I scanned it, getting a P0301 code, which points to a Cylinder 1 Misfire.

I'm not super mechanically inclined, but I'm wondering if this is something simple like a spark plug or ignition coil. The car has been pretty reliable up until now. Any ideas on what I should check first? Is this a common issue for the Mirage?

I'd appreciate any guidance on troubleshooting this. Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:05 AM

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ClearTheCode admin answer:

A P0301 code on your 2020 Mitsubishi Mirage G4 indicates a misfire detected in Cylinder 1. This is a common diagnostic code that can have several causes, ranging from simple to more complex.

Here's a breakdown of potential causes and diagnostic steps:

  1. Spark Plug: A worn, fouled, or improperly gapped spark plug in Cylinder 1 is a very common cause of misfires. Given your mileage, it's a good place to start. Spark plugs are relatively inexpensive and easy to replace on most engines.
  2. Ignition Coil: Each cylinder typically has its own ignition coil (coil-on-plug system). If the ignition coil for Cylinder 1 is failing, it won't provide adequate spark. You can often swap the coil from Cylinder 1 with one from another cylinder (e.g., Cylinder 2) and see if the misfire code moves (e.g., to P0302). If it does, the coil is likely faulty.
  3. Fuel Injector: A clogged, faulty, or dirty fuel injector for Cylinder 1 can prevent the cylinder from getting enough fuel, leading to a misfire. This is harder to diagnose without specialized tools, but fuel system cleaners can sometimes help with minor clogs.
  4. Compression Issue: Less common but more serious, a mechanical issue like a worn piston ring, damaged valve, or blown head gasket can cause low compression in Cylinder 1, leading to a misfire. This requires a compression test.
  5. Vacuum Leaks: While less likely to cause a single-cylinder misfire, a significant vacuum leak could affect air-fuel mixture, potentially leading to misfires.

When to see a shop:

If you're not comfortable checking spark plugs or swapping ignition coils, or if those steps don't resolve the issue, it's best to take your Mirage G4 to a professional mechanic. They can perform a comprehensive diagnosis, including:

  • Spark plug inspection and replacement.
  • Ignition coil testing.
  • Fuel injector flow testing.
  • Compression test to rule out internal engine problems.
  • Advanced scan tool diagnostics to monitor engine parameters and pinpoint the exact cause of the misfire.
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