U2939 – Lost Communication with the Steering Angle Sensor.

The ODBII code U2939 indicates a loss of communication with the steering angle sensor, which may affect the vehicle’s stability control and steering response systems.

The severity of ODBII code U2939 is generally considered moderate.

Common Causes For: U2937 U2937: Control Module Communication Bus Fault

• Faulty steering angle sensor
• Damaged wiring or connectors
• Poor electrical connections
• Malfunctioning power supply to the sensor
• Software issues or calibration errors
• Faulty vehicle control module (VCM)
• Interference from other electronic components

Common misdiagnosis for U2939 Lost Communication with the Steering Angle Sensor.

• Faulty Steering Angle Sensor
• Wiring Issues or Short Circuits
• Faulty Body Control Module (BCM)
• Faulty Electronic Power Steering (EPS) Module
• Incorrectly Calibrated Steering Angle Sensor
• Faulty ABS Module
• Issues with the CAN Bus Communication
• Battery or Power Supply Problems

Common Troubleshooting Steps

When dealing with the OBD-II code U2939, which indicates “Lost Communication with the Steering Angle Sensor,” there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Sometimes, related codes can provide more context for the issue.
• Inspect Wiring and Connectors: **Visual Inspection: Check the wiring harness and connectors associated with the steering angle sensor for any signs of damage, corrosion, or loose connections.
• **Connector Pins: Ensure that the pins in the connectors are not bent or corroded.
• Test the Steering Angle Sensor: **Sensor Functionality: If possible, test the steering angle sensor using a multimeter or scan tool to ensure it is functioning correctly.
• **Signal Output: Check the output signal of the sensor while turning the steering wheel to see if it changes appropriately.
• Check Power and Ground: **Power Supply: Verify that the steering angle sensor is receiving the correct voltage as specified in the vehicle’s service manual.
• **Ground Connection: Ensure that the ground connection for the sensor is solid and free of corrosion.
• Inspect the CAN Bus: **Communication Lines: Since the steering angle sensor communicates over the CAN bus, check for any issues with the CAN wiring. Look for shorts, opens, or interference.
• **CAN Bus Termination: Ensure that the CAN bus is properly terminated at both ends.
• Scan Tool Data: Use a scan tool to monitor live data from the steering angle sensor. Look for any irregularities in the data that could indicate a malfunction.
• Check for Software Updates: Sometimes, manufacturers release software updates that can resolve communication issues. Check if there are any updates available for the vehicle’s ECU.
• Inspect Related Modules: If the steering angle sensor is part of a larger system (like stability control), check other related modules for faults or communication issues.
• Clear Codes and Test Drive: After performing checks and repairs, clear the codes 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 related to the steering angle sensor and communication issues.1
• Professional Diagnosis: If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership, as they may have specialized tools and knowledge to diagnose the problem accurately. By following these steps, you should be able to identify the cause of the U2939 code and take appropriate action to resolve the issue.