Code Definition

P1165 — O2 Sensor Cross-counts (Bank 2 Sensor 3)

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: GM

About P1165

P1165 is a manufacturer-specific powertrain diagnostic trouble code recorded for GM vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1165 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.

P1165 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Engine Control Module (ECM) monitors the switching activity of the heated oxygen sensor located at bank 2 sensor 3, the rearmost sensor in that exhaust bank. Cross counts are the number of times the sensor signal crosses the stoichiometric threshold of approximately 450mV within a given sample period, and they indicate how quickly the sensor is responding to changes in exhaust oxygen content. DTC P1165 is set when the ECM determines that the cross count activity from this sensor is outside the expected range, either because the sensor is switching far too slowly (lazy or contaminated) or b...

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