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2020 Altima 2.5L Rough Idle & Check Engine Light - Misfire Codes?

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Mike T. · rep 0 · May 22, 2:53 AM · 1 replies · solved · Question

Vehicle: 2020 Nissan Altima 2.5L SR

Hi everyone,

My 2020 Nissan Altima 2.5L SR (around 60,000 miles) recently started running really rough, especially at idle. The check engine light came on yesterday, and it feels like the engine is struggling, almost like it's going to stall. I haven't had a chance to get the codes read yet, but I'm suspecting a misfire.

Could this be spark plugs or ignition coils already? 60k miles seems a bit early for spark plugs, but I've heard some Nissan engines can be particular. Has anyone else experienced this with their 2020 Altima? What were the common culprits and what OBD-II codes did you get?

Any insights or DIY tips for diagnosing this would be super helpful before I take it in!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 2:53 AM

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ClearTheCode admin answer:

It sounds like you're on the right track suspecting a misfire. A rough idle accompanied by a check engine light is a classic symptom. Here's a breakdown of what to check:

  1. Get the OBD-II Codes: This is your first and most crucial step. Most auto parts stores offer free code reading. Common misfire codes include:
    • P0300: Random/Multiple Cylinder Misfire Detected
    • P0301 - P0304: Cylinder 1-4 Misfire Detected (specifies which cylinder is misfiring)
  2. Common Causes for Misfires (2020 Altima 2.5L):
    • Ignition Coils: These are a very common failure point. A faulty coil will prevent spark to a specific cylinder. If you get a P030X code, you can often swap the coil with a known good cylinder to see if the misfire moves, confirming a bad coil.
    • Spark Plugs: While 60,000 miles isn't extremely high for modern iridium plugs, they can fail prematurely or become fouled. If you have a specific cylinder misfire, inspect that plug for fouling, damage, or incorrect gap.
    • Fuel Injectors: A clogged or faulty fuel injector can cause a cylinder to run lean or rich, leading to a misfire. This is less common than coils/plugs but still possible.
    • Vacuum Leaks: Unmetered air entering the engine can cause a lean condition and rough idle, sometimes triggering misfires.
    • Mass Air Flow (MAF) Sensor: A dirty or faulty MAF sensor can send incorrect air-fuel mixture data to the ECU, leading to performance issues.
  3. DIY Diagnostics:
    • Once you have the P030X code, you can visually inspect the ignition coil and spark plug for that cylinder. Look for cracks on the coil or unusual wear/fouling on the plug.
    • If you suspect a coil, you can try swapping it with an adjacent cylinder's coil. Clear the codes, drive the car, and if the misfire code moves to the new cylinder, you've found your faulty coil.
  4. When to See a Shop: If you're not comfortable working with ignition components, or if the problem persists after checking/replacing coils and plugs, it's best to take it to a professional. They have advanced diagnostic tools to pinpoint more complex issues like fuel system problems, compression issues, or ECU faults. Driving with a persistent misfire can damage your catalytic converter.
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