2001 Altima P0118 and P0101 Fault Codes Appearing Before Engine Cranks - MAF, ECT, Throttle Body Issues

I own a 2001 Nissan Altima with a 2.5L engine. The vehicle is throwing diagnostic trouble codes P0118 and P0101 before the engine is even cranked. I've already replaced both the Mass Airflow (MAF) sensor and the Engine Coolant Temperature (ECT) sensor. I also cleaned the throttle body manually, performed a full intake system cleaning from filter to throttle body, and replaced the air filter. The issue persists: these codes appear before engine cranking and cannot be cleared using my OBD2 scan tool. As a test, I disconnected the MAF sensor connector to intentionally trigger an intake air temperature fault. When reconnected, this specific code cleared immediately. However, P0118 and P0101 remain unresolved. This leads me to suspect either a faulty wiring harness or a malfunctioning Engine Control Unit (ECU). I've searched online but cannot find available ECU pinout diagrams for the 2.5L engine in this model year. An interesting observation: one user reported splicing an additional ground wire to the MAF sensor connector, which may have resolved their issue. This raises a question about potential grounding issues affecting sensor readings. I'm currently at a loss and would greatly appreciate any insights or troubleshooting steps from experienced owners or technicians.