Gas Recirculation Valve (egr Valve) problems of the 2021 Chevrolet Tahoe

Check engine light illuminated on my 2021 Chevrolet Tahoe. Upon diagnostic scan, the following emissions-related fault codes were present: p11d5 (nox sensor), p14d9 (nox sensor), p2383 (egr pressure sensor), and p2c7a (nox catalytic converter efficiency). All components are available for inspection upon request. The vehicle was taken to an authorized Chevrolet dealership for diagnosis. The dealer acknowledged the emissions codes but stated that unrelated components would need to be repaired at owner expense before the emissions system would be addressed, despite these codes falling within the federally mandated 8-year/80,000-mile emissions warranty. The fault codes were confirmed by the dealership. No safety incident has occurred to date, however degraded nox and egr function can result in increased harmful emissions output and potential engine performance issues. Warning lamps appeared without prior incident or symptom. The manufacturer has not offered to cover the emissions components under the federal emissions warranty without the owner first paying for additional repairs that may or may not be causally related to the emissions system failure. When the dealer was directly asked, "are you saying the emissions system itself is functioning correctly, and something else caused these codes to appear?" — the dealer did not provide an answer. This question was asked in order to clarify whether the emissions components themselves are degraded or failed, which would confirm warranty coverage eligibility. The dealer's failure to answer this question directly is noted as part of this complaint.