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Musty A/C smell & sluggish acceleration on 2021 NX 300h – Time for new air filters?

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

Vehicle: 2021 Lexus NX 300h Luxury

I have a 2021 Lexus NX 300h Luxury with about 35,000 miles. Lately, I've noticed a slightly musty smell coming from the A/C vents, and the airflow doesn't seem as strong as it used to be. Also, the car feels a little less responsive, almost sluggish, especially when accelerating from a stop.

Could these issues be related to dirty air filters? What are the service intervals for both the cabin air filter and the engine air filter on my hybrid NX? Are these easy DIY replacements?

✓ Accepted solution

ClearTheCode Admin

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

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  1. Cabin Air Filter:
    • Symptoms: A musty smell and reduced A/C airflow are classic signs of a clogged cabin air filter. Over time, it accumulates dust, pollen, leaves, and other debris, which can also harbor mold and bacteria causing odors.
    • Interval: Lexus typically recommends replacing the cabin air filter every 15,000 miles or 1 year. At 35,000 miles, yours is likely overdue if it hasn't been changed.
    • DIY: This is generally a very easy DIY job. The cabin air filter is usually located behind the glove box. You can find many online tutorials specific to the Lexus NX.
  2. Engine Air Filter:
    • Symptoms: Sluggish acceleration, reduced fuel economy, and a general lack of engine responsiveness can be caused by a dirty engine air filter. A clogged filter restricts airflow to the engine, making it "gasp" for air.
    • Interval: The engine air filter is typically recommended for replacement every 30,000 miles or 2 years. At 35,000 miles, yours is also due for replacement.
    • DIY: This is also a straightforward DIY task. The engine air filter is located in a plastic airbox under the hood. It usually involves unlatching clips or removing a few screws.
  3. Causes: Both filters accumulate debris from the environment. The cabin filter cleans air entering the passenger compartment, while the engine filter cleans air entering the engine for combustion.
  4. When to See a Shop: While both are easy DIYs, if you're uncomfortable or if replacing them doesn't resolve the issues (especially engine sluggishness), a shop can perform a more thorough diagnosis. A severely restricted engine air filter can sometimes trigger lean fuel trim codes (e.g., P0171, P0174) because the engine's computer detects too much air for the amount of fuel being injected, or vice-versa, but this is less common than simple performance degradation.
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