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2020 Escalade Misfire, Rough Idle, P030x Code

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Kevin B. · rep 0 · May 22, 4:00 AM · 1 replies · solved · Question

Vehicle: 2020 Cadillac Escalade ESV Premium Luxury

My 2020 Cadillac Escalade ESV Premium Luxury, with the 6.2L V8 and around 70,000 miles, just started running really rough. The check engine light came on, and when I scanned it, I got a P0304 code (Cylinder 4 Misfire). It idles poorly and feels like it's losing power when accelerating.

Could this be spark plugs, or something more serious like an ignition coil? I've heard these engines can be sensitive. I'm hoping it's not a major engine issue.

What's the best way to diagnose this further before I start throwing parts at it? Is this a DIY job for someone with moderate mechanical skills? Any specific tools I might need?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:00 AM

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A P0304 code on your 2020 Cadillac Escalade indicates a misfire specifically in cylinder 4. This is a common issue and can often be diagnosed and resolved without major engine work. The 6.2L V8 (L87) is generally robust, but ignition components do wear out.

Here's a systematic approach to diagnose and potentially fix the issue:

  1. Understand P030x Codes: P030x codes (where 'x' is the cylinder number) mean the Engine Control Module (ECM) detected a misfire in that specific cylinder. Common causes include issues with spark, fuel, or compression.
  2. Start with the Easiest:
    • Spark Plug: Given your mileage, spark plugs are a prime suspect. They are typically due for replacement around 75,000-100,000 miles. A worn or fouled plug can cause a misfire.
    • Ignition Coil: The ignition coil for cylinder 4 could be failing. This is also a very common cause.
  3. Diagnostic Steps (DIY with moderate skill):
    • Swap Components: The easiest way to confirm if it's the spark plug or coil is to swap them with an adjacent cylinder (e.g., move cylinder 4's coil to cylinder 2, and cylinder 4's spark plug to cylinder 6). Clear the code, drive the vehicle, and re-scan. If the misfire moves to cylinder 2 (P0302), it's the coil. If it moves to cylinder 6 (P0306), it's the spark plug.
    • Tools: You'll need a spark plug socket, ratchet, extensions, and potentially a torque wrench for proper installation.
  4. Other Potential Causes (if spark/coil swap doesn't work):
    • Fuel Injector: A clogged or faulty fuel injector for cylinder 4 could be starving it of fuel. This requires more advanced diagnostics.
    • Compression Issue: Low compression in cylinder 4 (due to valve issues, piston rings, or head gasket) is less common but serious. A compression test would confirm this.

When to See a Shop:

  • If swapping the spark plug and coil doesn't resolve the issue or move the misfire.
  • If you suspect a fuel injector problem or a compression issue, as these require specialized tools and expertise.
  • If the misfire is accompanied by unusual noises, smoke, or a strong smell of raw fuel, which could indicate a more severe problem.
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