The P0145 is a generic OBD-II powertrain trouble code. Its official definition is “O2 Sensor Circuit High Voltage (Bank 2, Sensor 3)”. This diagnostic trouble code is stored by the vehicle’s Engine Control Module (ECM) when it detects that the signal voltage from a specific oxygen sensor is consistently reading above the normal, expected range. The designation is critical: “Bank 2” refers to the side of the engine opposite the one containing cylinder number 1. “Sensor 3” indicates this is an additional sensor beyond the standard upstream (Sensor 1) and primary downstream (Sensor 2) sensors. Its function and location are vehicle-specific; it is often a secondary monitoring sensor in a complex exhaust system, perhaps after an additional catalytic converter.
