Code Definition

P0136 — O2 A/F Sensor Circuit B1 S2

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

About P0136

P0136 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 P0136 is stored, the module has detected 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 P0136 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 bank 1 sensor 2 oxygen sensor is mounted in the exhaust downstream of the catalytic converter, where its primary role is monitoring converter efficiency rather than controlling fuel delivery. A conventional zirconia sensor generates its own voltage, switching between roughly 0.1V in a lean exhaust and 0.9V in a rich exhaust, and on a healthy vehicle the downstream signal sits relatively steady around 0.6V to 0.7V because the converter has evened out the oxygen content. P0136 sets when the ECM detects the sensor circuit outside its expected operating range, covering a signal stuck at a fixe...

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