The P0144 is a generic OBD-II powertrain trouble code. Its official definition is “O2 Sensor Circuit High Voltage (Bank 1, Sensor 3)”. This code is stored by the vehicle’s Engine Control Module (ECM) when it detects that the signal voltage from a specific oxygen sensor is persistently and abnormally high, typically near the reference or battery voltage level. The sensor designation is key: “Bank 1” refers to the side of the engine containing cylinder number 1. “Sensor 3” is not a standard upstream or primary downstream sensor; it is an additional sensor found in some vehicles, often a secondary downstream monitor.
