2006 Cadillac CTS P0103 Code Reappears After MAF Replacement - How to Fix?

I own a 2006 Cadillac CTS with a 3.6L engine. The vehicle is displaying a Diagnostic Trouble Code (DTC) P0103: Mass Air Flow (MAF) Circuit High Input. The check engine light is on, and I've scanned the system to confirm the code. I replaced the MAF sensor and cleaned both the sensor and its wiring harness. I also disconnected the signal wire from the insulation to inspect for any frays or open circuits—no issues were found. After reinstallation, the check engine light returned immediately, even after resetting via an OBD2 scanner. I tested the voltage output from the MAF sensor, which showed abnormal readings. I then replaced the MAF sensor again, restarted the vehicle, and cleared the code. The car ran normally during a one-hour drive to the city center. However, upon restarting the engine later, the P0103 code reappeared. After clearing it once more, the light stayed off for some time but returned after shutting down and restarting the vehicle. This issue is very frustrating—especially since I'm trying to sell the car. A persistent check engine light significantly reduces its market value. I would not consider purchasing a vehicle with this code active. Any advice or troubleshooting steps would be greatly appreciated.