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Rough idle & slight MPG drop on 2016 ES 350 – Time for new spark plugs?

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Mike T. · rep 0 · May 25, 3:29 AM · 1 replies · solved · Question

Vehicle: 2016 Lexus ES 350

My 2016 Lexus ES 350 has about 95,000 miles on it now, and I've started noticing a slightly rougher idle than usual. It's not terrible, but it's definitely not as smooth as it used to be. I also feel like my gas mileage has dipped a little bit over the last few months.

I'm wondering if it's time to replace the spark plugs. What's the recommended interval for the ES 350, and is this a DIY job I can tackle, or should I leave it to the pros? Any tips or things to watch out for if I try it myself?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:29 AM

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  1. Spark Plug Interval: For your 2016 Lexus ES 350 (likely with the 3.5L 2GR-FE V6 engine), the recommended spark plug replacement interval is typically every 60,000 to 100,000 miles for iridium-tipped plugs. At 95,000 miles, you are definitely within the window where replacement is due or overdue.
  2. Symptoms: Rough idle, slight MPG drop, and even a minor loss of power are classic symptoms of worn spark plugs. Plugs that are past their prime can lead to incomplete combustion, causing these issues.
  3. DIY Considerations:
    • Accessibility: The front bank of cylinders is relatively easy to access. The rear bank, however, is under the intake manifold, making it a more involved job.
    • Tools: You'll need a spark plug socket, various extensions, a torque wrench, and potentially a gasket for the intake manifold if you remove it.
    • Parts: Use OEM equivalent iridium spark plugs (e.g., Denso or NGK are common OEM suppliers for Lexus).
    • Procedure: Ensure the engine is cool. Disconnect the battery. Remove ignition coils carefully. Torque new plugs to specification. If removing the intake manifold, replace its gaskets.
  4. Causes: Over time, the electrodes on spark plugs erode, increasing the gap and requiring more voltage to spark, leading to misfires and inefficient combustion. Carbon buildup can also foul the plugs.
  5. When to See a Shop: If you're not comfortable removing the intake manifold or don't have the necessary tools, it's best to have a professional technician handle it. Incorrect installation or torquing can lead to engine damage. If you've been driving with significant misfires, you might also see OBD codes like P0301, P0302, etc. (Misfire Cylinder 1, 2, etc.), which a shop can diagnose.
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