U1279 – Invalid or Missing Data for Vehicle Speed.

The ODBII code U1279 indicates that the vehicle’s control module has detected invalid or missing data related to vehicle speed, which may affect the performance of various systems.

The severity of ODBII code U1279 is moderate.

Common Causes For: U1278 U1278: “Module Communication Failure”

• 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 ABS module (if applicable)

Common misdiagnosis for U1279 Invalid or Missing Data for Vehicle Speed.

• Faulty Vehicle Speed Sensor (VSS)
• Malfunctioning Engine Control Module (ECM)
• Wiring issues or short circuits in the speed sensor circuit
• Faulty ABS module
• Incorrect tire size or calibration issues
• Transmission problems
• Faulty instrument cluster
• Issues with the CAN bus communication system

Common Troubleshooting Steps

The OBD-II code U1279 indicates an “Invalid or Missing Data for Vehicle Speed.” This code typically points to a communication issue between the vehicle’s modules, particularly related to the vehicle speed sensor (VSS) or the data being transmitted over the CAN (Controller Area Network) bus. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Codes related to the transmission, speed sensor, or other modules can provide additional context.
• Inspect Vehicle Speed Sensor (VSS): Locate the vehicle speed sensor and inspect it for any physical damage or disconnection.
• Check the wiring and connectors for corrosion, fraying, or loose connections.
• Test the VSS with a multimeter to ensure it is functioning correctly. Refer to the vehicle’s service manual for specific resistance values.
• Examine Wiring and Connectors: Inspect the wiring harnesses and connectors associated with the VSS and the modules that communicate vehicle speed data.
• Look for any signs of wear, damage, or poor connections that could affect data transmission.
• Check the CAN Bus: Use a scan tool to monitor the CAN bus for any communication issues. Ensure that all modules are communicating properly.
• Look for any other codes that may indicate a problem with the CAN bus or other modules.
• Test the Instrument Cluster: If the vehicle speed data is not being displayed correctly on the instrument cluster, the cluster itself may be faulty.
• Check for any issues with the cluster’s connections and functionality.
• Inspect the Transmission Control Module (TCM): The TCM may also be involved in processing vehicle speed data. Check for any faults or communication issues with the TCM.
• Check for Software Updates: Some vehicles may require software updates for the engine control module (ECM) or other modules. Check with the manufacturer for any available updates.
• Clear Codes and Test Drive: After performing any repairs or inspections, clear the trouble codes using the OBD-II scanner.
• Take the vehicle for a test drive to see if the code reappears. Monitor the vehicle speed data during the drive.
• Consult a Professional: 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.Conclusion Troubleshooting OBD-II code U1279 involves a systematic approach to identify and resolve issues related to the vehicle speed sensor and communication between modules. By following these steps, you can often pinpoint the problem and take appropriate corrective action.