VW GTI MK5 2006 P0237 Fault: Sensor No Power, Voltage Test Results

I recently purchased a 2006 VW GTI MK5 2.0T and am experiencing a recurring P0237 diagnostic trouble code. Initially, the vehicle had a P0203 code, which led me to replace all fuel injectors, coil packs, and spark plugs. After clearing the codes and performing a test start, I now receive a P0237 code. I attempted to verify the sensor functionality by unplugging the oxygen sensor during startup — the engine ran smoothly on idle at that time. However, once I reconnected the sensor and cleared the codes again, the P0237 code returned immediately. After replacing the sensor, it only functioned for about 15 minutes before the code reappeared upon shutdown. I tested the wiring to the sensor: one wire (black) shows proper ground connection, while the other two wires show no voltage or continuity to ground when the engine is running. I also performed a back-probe test with the engine on — still no signal. The issue appears to be related to power delivery to the sensor, but I'm unsure whether it's a wiring fault, faulty harness, or an underlying ECU problem. Any insights into diagnosing this P0237 code specifically in a 2006 VW GTI MK5 would be greatly appreciated.