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Check Engine Light P030X and Rough Idle on 2018 Regal TourX

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Mark S. · rep 0 · May 22, 3:49 AM · 1 replies · solved · Question

Vehicle: 2018 Buick Regal TourX Essence

Hello Buick forum! I'm having some trouble with my 2018 Buick Regal TourX, 2.0L turbo. The check engine light came on a few days ago, and the car has developed a really rough idle. It feels like the engine is shaking, and sometimes it even stumbles when I'm at a stoplight.

I used an OBD scanner and pulled a P0301 code, indicating a misfire on cylinder 1. I'm wondering if this is a common issue for the 2.0L engine in these Regal models. What should I be looking at first to troubleshoot this? Any advice would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:49 AM

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ClearTheCode admin answer:

A P0301 code on your 2018 Buick Regal TourX 2.0L turbo, indicating a misfire on cylinder 1, is a common issue across many modern engines and points directly to a problem affecting combustion in that specific cylinder. The rough idle and stumbling are direct symptoms of this misfire.

Common Causes & Diagnostics for P0301:

  1. Spark Plug: A worn, fouled, or damaged spark plug in cylinder 1 is a very frequent cause of misfires. It's often the first thing to check.
  2. Ignition Coil: The ignition coil for cylinder 1 might be failing. The coil provides the high voltage to the spark plug. You can often swap the coil from cylinder 1 to another cylinder (e.g., cylinder 2) and see if the misfire code follows (e.g., changes to P0302). This is a good diagnostic step.
  3. Fuel Injector: A clogged, faulty, or leaking fuel injector for cylinder 1 can prevent the correct amount of fuel from reaching the cylinder, leading to a misfire.
  4. Compression Issue: Less common, but a serious cause could be low compression in cylinder 1 due to issues like a worn piston ring, a bent valve, or a blown head gasket. This would require a compression test.
  5. Vacuum Leak: A vacuum leak near cylinder 1 could lean out the air/fuel mixture, causing a misfire.
  6. PCV System: On these 2.0L engines, issues with the PCV system can sometimes lead to oil consumption and spark plug fouling, contributing to misfires.

When to See a Shop:

  • Soon: If replacing the spark plug and swapping the ignition coil doesn't resolve the issue.
  • Immediately: If the check engine light is flashing, which indicates a severe misfire that could damage the catalytic converter. A professional can perform advanced diagnostics, including fuel pressure tests, injector pulse tests, and compression tests, to accurately identify the root cause and prevent further engine damage.
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