Code Definition

P1168 — Primary Heated Oxygen Sensor (#1) low input

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

About P1168

P1168 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 P1168 is stored, the module has detected a signal or supply voltage lower than the expected operating range; 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.

P1168 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 primary bank 1 air fuel ratio sensor reports the exhaust air fuel ratio to the Engine Control Module (ECM) as a varying signal used for closed loop fuel control, normally moving across its range as the mixture cycles. DTC P1168 sets when the ECM detects this signal staying consistently low, typically near or below 0.1V on a conventional sensor, during closed loop operation. A persistently low signal means the sensor is reporting a steady lean condition, or the signal circuit is shorted to ground or has lost its reference. The cause may be a genuine lean mixture or an electrical fault. The ...

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