Code Definition

P1149 — Primary Heated Oxygen Sensor (#1) circuit

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

About P1149

P1149 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 P1149 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.

P1149 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 or upstream heated oxygen sensor, HO2S Sensor 1 on bank 1, generates a voltage that reflects the oxygen content of the exhaust and is the main input the Engine Control Module (ECM) uses for closed loop fuel control. The signal normally swings between roughly 0.1V and 0.9V as the mixture cycles rich and lean. DTC P1149 sets when the ECM detects the sensor circuit reading out of the expected range, fixed, missing, or erratic, indicating an electrical fault in the signal, ground, or heater circuit rather than a slow response. When set, the ECM defaults to open loop fuel control, which...

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