Code Definition

P1133 — HO2S Insufficient Switching Sensor 1

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

About P1133

P1133 is a manufacturer-specific powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1133 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.

P1133 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

This code sets when the powertrain control module (PCM) detects that the upstream heated oxygen sensor (HO2S) is not switching between rich and lean conditions as frequently as expected. The PCM monitors the response rate of the sensor, and if it is too slow, it may indicate a failing sensor or issues affecting the air-fuel mixture.

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