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MANUFACTURER DOCUMENTATION

GMC Sierra

Airbox/catalyst diagnostic evidence.

Documented years: 2014–2018

Match the document’s model, years, engine, market and other conditions. This page does not establish every code the vehicle can display.

Diagnostic guides

Silverado and Sierra P0420/P0430: check the airbox before exhaust parts

Look for an intake sealing failure before authorizing catalyst or oxygen-sensor work.

Manufacturer bulletins

Catalyst codes with air-filter sealing concerns

Read the full diagnostic guide.

Scope: 2014–2018 Sierra; 2015–2018 Yukon · Sierra: L83/L86/LV1/LV3; Yukon: L83/L86

Displays in the document: P0420, P0430

See the documented decision branches.

Vehicle-specific scope applies.

Read the diagnostic case guide

Sources and scope

  1. 16-NA-111 version 3

    General Motors · Checked 2026-10-30

  2. 2017 Silverado owner manual — engine air cleaner

    General Motors · Checked 2026-10-30

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