WOMS
U code network Medium severity

U1271 Invalid or Missing Data for Vehicle Speed

The OBD2 code U1271 indicates that the vehicle's control module has detected invalid or missing data related to the vehicle speed, which may affect performance and diagnostics

Definition

The OBD2 code U1271 indicates that the vehicle's control module has detected invalid or missing data related to the vehicle speed, which may affect performance and diagnostics

Common causes

  • Faulty vehicle speed sensor
  • Damaged wiring or connectors
  • Faulty engine control module (ECM)
  • Faulty transmission control module (TCM)
  • Poor ground connections
  • Corroded or damaged connectors
  • Software issues or glitches in the ECM/TCM
  • Issues with the CAN bus communication system

Common misdiagnoses

  • Faulty Vehicle Speed Sensor (VSS)
  • Malfunctioning Engine Control Module (ECM)
  • Wiring issues or short circuits
  • Faulty ABS module
  • Incorrect tire size or calibration
  • Transmission issues
  • Problems with the instrument cluster
  • Faulty or corroded connectors
  • Issues with the CAN bus communication
  • Faulty cruise control system

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Addressing related codes can help in diagnosing the issue more effectively

  2. 2. Inspect Vehicle Speed Sensor (VSS)

    Visual Inspection: Check the VSS for any physical damage, loose connections, or corrosion at the connector

  3. 3. Wiring Check

    Inspect the wiring harness for any frays, shorts, or disconnections

  4. 4. Testing

    Use a multimeter to test the VSS for proper voltage and resistance according to the manufacturer's specifications

  5. 5. Check the Instrument Cluster

    Ensure that the instrument cluster is functioning correctly. If the speedometer is not working, it may indicate a problem with the cluster itself

  6. 6. Inspect Communication Lines

    Check the CAN (Controller Area Network) bus lines for continuity and proper connections. Look for any signs of damage or corrosion

  7. 7. Ensure that all control modules are communicating properly. You can use a scan tool to monitor data from different modules

  8. 8. Check for Ground Issues

    Ensure that all ground connections related to the VSS and control modules are secure and free of corrosion

  9. 9. Test the PCM (Powertrain Control Module)

    If the VSS and wiring are functioning correctly, the issue may lie within the PCM. Check for software updates or reprogramming if necessary

  10. 10. Inspect Related Components

    Check other components that may affect vehicle speed readings, such as the ABS (Anti-lock Braking System) module, as it may also use vehicle speed data

  11. 11. Clear Codes and Test Drive

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

  12. 12. Seek Professional Help

    If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with your specific vehicle make and model. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the U1271 code