U1271 – Invalid or Missing Data for Vehicle Speed.

The ODBII 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.

The severity of ODBII code U1271 is moderate.

Common Causes For: U1270 Invalid or Missing Data from Vehicle Speed Sensor.

• 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 misdiagnosis for U1271 Invalid or Missing Data for Vehicle Speed.

• 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

Common Troubleshooting Steps

The OBD-II code U1271 indicates an “Invalid or Missing Data for Vehicle Speed.” This code typically points to a communication issue between the vehicle’s control modules, particularly related to the vehicle speed sensor (VSS) or the data being transmitted. 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. Addressing related codes can help in diagnosing the issue more effectively.
• Inspect Vehicle Speed Sensor (VSS): **Visual Inspection: Check the VSS for any physical damage, loose connections, or corrosion at the connector.
• **Wiring Check: Inspect the wiring harness for any frays, shorts, or disconnections.
• **Testing: Use a multimeter to test the VSS for proper voltage and resistance according to the manufacturer’s specifications.
• 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.
• Inspect Communication Lines: Check the CAN (Controller Area Network) bus lines for continuity and proper connections. Look for any signs of damage or corrosion.
• Ensure that all control modules are communicating properly. You can use a scan tool to monitor data from different modules.
• Check for Ground Issues: Ensure that all ground connections related to the VSS and control modules are secure and free of corrosion.
• 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.
• 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.
• 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.
• Consult Service Manual: Refer to the vehicle’s service manual for specific diagnostic procedures and specifications related to the VSS and communication protocols.
• 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.