U0142

U0142 refers to a diagnostic trouble code (DTC) that may be present in vehicles equipped with On-Board Diagnostics (OBD-II) systems. Specifically, it relates to issues with the heated oxygen sensor (HO2S) circuit for Bank 1 Sensor 2.

The oxygen sensor is a critical component in the exhaust system that measures the amount of unburned oxygen. This information is used by the vehicle's engine control module (ECM) to adjust the air-fuel mixture for optimal combustion. Bank 1 refers to the side of the engine that contains cylinder number one, while Sensor 2 indicates the second oxygen sensor in the exhaust stream, typically located downstream of the catalytic converter.

When the ECM detects a problem with the circuit of the Bank 1 Sensor 2, such as an open circuit, short to ground, or short to voltage, it will trigger the U0142 DTC and illuminate the Malfunction Indicator Lamp (MIL), commonly known as the check engine light.

Common causes for this code can include a faulty heated oxygen sensor, damaged wiring or connectors in the sensor's circuit, or an issue with the ECM itself. Symptoms may include reduced fuel efficiency, rough idling, increased emissions, and potentially a failing emissions test. Diagnosis typically involves checking the wiring harness, testing the oxygen sensor's resistance and response, and verifying the ECM's functionality.