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2018 Buick Enclave Premium - Rough Idle, Misfire, and Check Engine Light

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Mike T. · rep 0 · May 24, 1:34 PM · 1 replies · solved · Question

Vehicle: 2018 Buick Enclave Premium

Hey everyone,

I'm having some trouble with my 2018 Buick Enclave Premium, which has about 75,000 miles on it. Lately, I've noticed a really rough idle, especially when I'm stopped at a light or in park. The whole car shakes a bit, and it feels like the engine is struggling.

To top it off, the Check Engine Light came on a couple of days ago and hasn't gone off. I haven't noticed any significant loss of power while driving, but the rough idle is definitely concerning. I recently had an oil change, but nothing else major.

I'm wondering if anyone else with a 2016-2026 Enclave or similar Buick model has experienced this? What could be causing these symptoms? Any advice on what I should check before taking it to a mechanic would be greatly appreciated. Thanks in advance!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 24, 1:34 PM

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ClearTheCode admin answer:

It sounds like your 2018 Buick Enclave Premium is experiencing a common issue related to engine misfires, which can definitely cause a rough idle and trigger the Check Engine Light (CEL). Here’s a breakdown of potential causes and what you can do:

1. Check for OBD-II Codes: The first and most crucial step is to get the diagnostic trouble codes (DTCs) read. You can often do this for free at most auto parts stores. Common codes for misfires include:

  • P0300: Random/Multiple Cylinder Misfire Detected
  • P0301-P0306: Cylinder Misfire Detected (the last digit indicates the specific cylinder, e.g., P0301 for cylinder 1).

2. Common Causes of Misfires:

  • Ignition System:
    • Worn Spark Plugs: Over time, spark plugs wear out, leading to weak or inconsistent spark.
    • Faulty Ignition Coils: A failing ignition coil on one or more cylinders can prevent proper spark.
  • Fuel System:
    • Clogged Fuel Injectors: An injector that's not delivering enough fuel can cause a lean misfire.
    • Low Fuel Pressure: Issues with the fuel pump or fuel pressure regulator.
  • Air/Vacuum Leaks:
    • Vacuum Leaks: Unmetered air entering the engine can disrupt the air-fuel mixture, causing misfires. Check hoses and gaskets.
    • Mass Air Flow (MAF) Sensor: A dirty or failing MAF sensor can send incorrect air readings to the engine computer.
  • Engine Mechanical Issues (Less Common but Possible):
    • Low compression in a cylinder due to worn piston rings or valve issues.

3. When to See a Shop: While checking codes is a good start, diagnosing the exact cause of a misfire can be complex. You should definitely see a qualified mechanic if:

  • The Check Engine Light is flashing: This indicates a severe misfire that could damage the catalytic converter.
  • You experience a significant loss of power or acceleration.
  • The rough idle persists after basic checks, or you're uncomfortable performing inspections yourself.
  • The OBD-II codes point to multiple cylinders or issues beyond simple spark plug replacement.

A professional can perform more in-depth diagnostics, such as live data monitoring, compression tests, and fuel pressure checks, to accurately pinpoint the problem and prevent further damage to your Enclave.

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