Code Definition

P0140 — O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)

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

About P0140

P0140 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 P0140 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 P0140 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 P0140 fault code is triggered when the Engine Control Module (ECM) detects no activity or insufficient activity from the oxygen sensor in Bank 1, Sensor 2. This sensor is generally located downstream in the exhaust system, after the catalytic converter. 'No activity' means that the sensor is not providing the varying voltage output expected to indicate changing oxygen levels in the exhaust. This lack of activity can be due to a faulty sensor, an issue with the wiring or connections, or an exhaust leak affecting the sensor's ability to detect oxygen levels accurately. The ECM uses this down...

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