Code Definition

P1165 — Primary Heated Oxygen Sensor (#1) circuit

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

About P1165

P1165 is a manufacturer-specific powertrain diagnostic trouble code recorded for Acura 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 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

On these Honda and Acura engines the primary bank 1 sensor is a multi wire wide band air fuel ratio sensor whose signal and reference circuits the Engine Control Module (ECM) uses for closed loop fuel control. The ECM continuously checks that the sensor circuit produces a valid, consistent signal. DTC P1165 sets when the ECM detects the primary sensor circuit failing to meet its calibrated operating parameters, with the expected signal absent, fixed, or inconsistent during closed loop operation. This often reflects a wiring, connector, or reference circuit problem across the several wires the ...

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