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U code network Medium severity

U1142 SCP (J1850) Invalid or Missing Data for Primary Id

The OBD2 code U1142 SCP (J1850) indicates that there is invalid or missing data for the primary identifier in the vehicle's communication network, which may affect the proper functioning of certain systems

Definition

The OBD2 code U1142 SCP (J1850) indicates that there is invalid or missing data for the primary identifier in the vehicle's communication network, which may affect the proper functioning of certain systems

Common causes

  • Faulty or damaged wiring/connectors
  • Malfunctioning or disconnected sensors
  • Issues with the vehicle's communication network
  • Faulty PCM (Powertrain Control Module)
  • Corrupted or outdated software/firmware
  • Interference from aftermarket devices
  • Poor ground connections
  • Low battery voltage or weak battery
  • Faulty or incompatible OBD-II scanner/reader

Common misdiagnoses

  • Faulty vehicle speed sensor
  • Malfunctioning engine control module (ECM)
  • Wiring issues or short circuits
  • Faulty communication network (CAN bus)
  • Defective instrument cluster
  • Incorrectly programmed or updated software
  • Bad ground connections
  • Issues with other control modules (e.g., ABS, transmission control module)

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 other codes may resolve the U1142 issue

  2. 2. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors related to the affected modules. Look for signs of damage, corrosion, or loose connections

  3. 3. Pay special attention to the wiring harnesses that connect to the primary control module

  4. 4. Check the Battery and Ground Connections

    Ensure that the vehicle's battery is fully charged and in good condition

  5. 5. Check the ground connections for the control modules. Poor ground connections can lead to communication issues

  6. 6. Test the Control Modules

    Identify the primary control module that is referenced in the code. This could be the PCM (Powertrain Control Module), BCM (Body Control Module), or another module

  7. 7. Use a scan tool to check if the module is functioning properly and communicating with other modules

  8. 8. Perform a Network Test

    Use a scan tool capable of performing a network test to check the communication between modules on the SCP bus

  9. 9. Look for any modules that are not responding or are showing communication errors

  10. 10. Check for Short Circuits or Open Circuits

    Use a multimeter to check for short circuits or open circuits in the wiring harnesses associated with the SCP bus

  11. 11. Ensure that the resistance and voltage levels are within specifications

  12. 12. Inspect for Interference

    Check for any aftermarket devices or modifications that may interfere with the vehicle's communication network

  13. 13. Remove or disconnect any non-factory equipment to see if the issue persists

  14. 14. Update or Reprogram Modules

    If the control module is not responding correctly, it may need to be reprogrammed or updated with the latest software from the manufacturer

  15. 15. Clear Codes and Test Drive

    After performing the above checks and repairs, clear the trouble codes using the scan tool

  16. 16. Take the vehicle for a test drive to see if the code returns

  17. 17. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the U1142 code for your specific vehicle make and model. Manufacturers may have specific fixes or recommendations.1

  18. 18. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who specializes in automotive electronics and diagnostics. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the U1142 code