Code Definition

P0142 — O2 Sensor Circuit Malfunction (Bank 1 Sensor 3)

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0142

P0142 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0142 is stored, the module has detected a bank-specific fault, meaning it applies only to one cylinder bank of a multi-bank engine; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0142 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The P0142 fault code is set when the Engine Control Module (ECM) detects a malfunction in the circuit of the oxygen sensor located in Bank 1, Sensor 3. This sensor is typically positioned downstream in the exhaust system and is often used in vehicles with multiple catalytic converters or specialized emission control systems. The malfunction could be related to the sensor itself, such as failing to produce the correct voltage range, or it might involve issues with the wiring or connectors that link the sensor to the ECM. The ECM relies on this sensor for accurate monitoring of the exhaust gas c...

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