Code Definition

P1900 — OSS Circuit Intermittent Malfunction

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

About P1900

P1900 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 P1900 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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.

P1900 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 P1900 fault code indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected an intermittent issue with the Output Shaft Speed (OSS) sensor circuit. This means the sensor signal is unstable, dropping out sporadically, or fluctuating beyond acceptable limits. The module monitors the OSS sensor signal to ensure it remains within a specified frequency range, and if inconsistencies occur, the fault is logged.

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