K1O ✓ Factory-verified

Buick · Regular Production Option

Engine air filtration monitor

Years 2025–27 Models 3 Factory citations 10

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Also described as Engine, air filtration monitor

Also documented for CadillacChevroletGMC

Documented applications

Encore GX — VSS-F (2020–2027) →

• 2025–2027 ✓ Factory-verified

  Preferred, Sport Touring, Avenir: S; letter O in the code as GM prints it; GM prints no zero form

  ⛭ GM factory document — 2025 buick encore gx fleet order guide, p.8.

  ⛭ GM factory document — 2026 buick encore gx fleet order guide, p.8.

  ⛭ GM factory document — 2027 buick encore gx fleet order guide, p.8.

Envision — E2XX (2021–2027) →

• 2025–2027 ✓ Factory-verified

  2027: all trims: S; letter O in the code as GM prints it; GM prints no zero form

  ⛭ GM factory document — 2025 buick envision fleet order guide rpo codes, p.1.

  ⛭ GM factory document — 2027 buick envision fleet order guide rpo codes, p.1.

  ⛭ GM factory document — 2027 buick envision fleet order guide, p.7.

Envista — VSS-F (2024–2027) →

• 2025–2026 ✓ Factory-verified

  all trims: S

  ⛭ GM factory document — 2025 buick envista fleet order guide rpo codes, p.1.

  ⛭ GM factory document — 2025 buick envista fleet order guide, p.6.

  ⛭ GM factory document — 2026 buick envista fleet order guide rpo codes, p.1.

  ⛭ GM factory document — 2026 buick envista fleet order guide, p.6.

This page aggregates every documented appearance of K1O in the Buick reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.