NHTSA Complaint #11716603 — 2017 HYUNDAI SONATA

My 2017 Hyundai Sonata Hybrid has a permanent and recurring DTC P1326 (Knock signal range/performance) from the Knock Sensor Detection System (KSDS), indicating potential connecting rod bearing wear in the Nu 2.0L engine. The vehicle enters limp mode (reduced power, limited acceleration/speed) on the highway under load, with hard engine vibration, tinkling/knocking noise from under hood, and significantly reduced MPG. These symptoms create a serious safety risk: sudden loss of power at highway speeds (e.g., 50+ mph) makes it difficult to maintain speed, merge, or avoid hazards, increasing crash risk or stranding in traffic. In rare cases, bearing wear can lead to engine seizure or failure. The problem first appeared summer 2024 at approximately 115,000 miles. The Check Engine Light illuminates (cristmass tree), and limp mode triggers during highway driving. I have an OBD scan showing confirmed, pending, and permanent P1326, plus related hybrid communication codes (U0293, U1004) likely secondary to the protection mode. The vehicle has been inspected multiple times (four visits) by a Hyundai dealer. Each time they scanned the code, performed basic checks, but stated “engine is working normal, no road vibration, nothing” and did not resolve the issue. The code returns immediately after clearing. I replaced the knock sensor, engine mounts, spark plugs, ignition coils myself—did not fix it. Dealers did not perform the full bearing clearance test or follow TSB 22-01-023H (Service Campaign T6G) procedure as required for this known issue (related to Recall 209 and Campaign 966). The component (engine/connecting rod bearings) is still in the vehicle and available for inspection. No police, insurance, or other parties have inspected it beyond the dealer. This matches a widespread known defect in 2011–2019 Sonata Hybrids (bearing wear triggering P1326/limp mode).