GM's new PIE0905 bulletin targets MIL illumination and DTC P0101 on 2025-2026 LZ0 Duramax models (Silverado 1500, Sierra 1500, Tahoe, Suburban, Yukon). It's an early data-collection step: dealers gather intake leak/test details to help engineers identify root causes before issuing a full TSB fix. U.S. dealers only—contact required before repairs. If your truck shows this code, see a dealer soon.