NHTSA Complaint #11717379 — 2023 GMC YUKON XL

POST-RECALL 25V274 ( & EA25007, EA25001) EXHAUST INTRUSION WITH CARBON MONOXIDE POISONING HAZARD Following the complete engine replacement under GM recall N252494000, my vehicle has developed a severe and persistent exhaust intrusion that allows toxic exhaust fumes, including carbon monoxide (CO), to enter the passenger cabin. CO levels have measured a peak of 83 PPM and consistent reading between 20-37 over multiple tests. PATTERN OF POST-RECALL EXHAUST SYSTEM FAILURES Vehicle has been in for service 6 times, over 100 days, as part of the engine replacement plus (metal found in the oil pan). Since recall, the vehicle has had an exhaust smell and noise rattle issue with the following exhaust system components deemed failed and been replaced: 1. Radiator cap (leaking onto exhaust) 2. Exhaust muffler (replaced TWICE - June 2025 and August 2025) 3. Exhaust clamps (leaking) 4. Left exhaust manifold (warped) Critical Finding: Despite replacement of virtually the entire exhaust system, the defect persists. This suggests a fundamental design or installation defect related to the engine replacement procedure, NOT isolated component failures. Documented Carbon Monoxide Levels: Between January 30 and February 3, 2026, I conducted 15+ tests using a professional-grade Klein Tools ET180 Carbon Monoxide Meter. Results: • Peak reading: 83 PPM • Multiple readings: 40-72 PPM sustained for 6+ minutes directly at my [XXX] daughter's car seat position • Testing method: Vehicle started via remote start, CO meter placed in cabin, readings recorded over 10-15 minute periods Health Impacts to Family: • Wife and [XXX] daughter consistently experience dizziness, headaches, and nausea when riding in vehicle • Daughter now refuses to ride in vehicle because it makes her feel sick • Symptoms consistent with carbon monoxide poisoning Independent service station verification on January 30th confirmed "vehicle is dangerous to operate with children inside and needs immediate service." INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMA