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P code powertrain Medium severity

P1900 OSS Circuit Intermittent Malfunction

The OBD2 code P1900 indicates an intermittent malfunction in the Output Shaft Speed (OSS) circuit, which is responsible for monitoring the speed of the output shaft in the transmission

Definition

The OBD2 code P1900 indicates an intermittent malfunction in the Output Shaft Speed (OSS) circuit, which is responsible for monitoring the speed of the output shaft in the transmission

Common causes

  • Faulty OSS (Output Shaft Speed) sensor
  • Poor electrical connections or wiring issues
  • Corroded connectors
  • Intermittent sensor signal
  • Faulty transmission control module (TCM)
  • Software issues or glitches in the TCM
  • Mechanical issues within the transmission
  • Low transmission fluid levels or contamination

Common misdiagnoses

  • Transmission fluid issues
  • Faulty speed sensors
  • Wiring or connector problems
  • Transmission control module (TCM) failure
  • Engine control module (ECM) issues
  • Incorrectly diagnosed transmission problems
  • Faulty vehicle speed sensor (VSS)
  • Problems with the ABS system
  • Electrical shorts or open circuits
  • Software or calibration errors in the TCM or ECM

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue

  2. 2. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors associated with the OSS sensor. Look for signs of damage, corrosion, loose connections, or frayed wires. Repair or replace any damaged components

  3. 3. Test the OSS Sensor

    Use a multimeter to test the OSS sensor's resistance and voltage output. Compare the readings to the manufacturer's specifications. If the sensor is out of spec, it may need to be replaced

  4. 4. Check the Transmission Fluid

    Ensure that the transmission fluid is at the correct level and in good condition. Low or contaminated fluid can affect sensor performance

  5. 5. Inspect the Transmission Control Module (TCM)

    Check for any issues with the TCM, as it processes signals from the OSS sensor. Ensure that the TCM is functioning correctly and that there are no software issues

  6. 6. Look for Mechanical Issues

    Inspect the transmission for any mechanical problems that could affect the OSS sensor's operation, such as worn gears or internal damage

  7. 7. Clear the Codes and Test Drive

    After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner. Take the vehicle for a test drive to see if the code reappears

  8. 8. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the OSS sensor or transmission issues for your specific vehicle make and model. Manufacturers may have issued guidance on common problems and fixes

  9. 9. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with transmission systems and OBD-II diagnostics. By following these steps, you can systematically diagnose and address the P1900 code and its underlying causes