U2420 – Vehicle Speed Signal Communication Error
The ODBII code U2420: Vehicle Speed Signal Communication Error indicates a problem with the communication of the vehicle speed signal between the engine control module (ECM) and other control modules, which may affect vehicle performance and systems relying on speed data.
The severity of ODBII code U2420 is moderate.
Common Causes For: U2419 U2419: Transmission Control Module Communication Error
- Faulty vehicle speed sensor
- Damaged wiring or connectors
- Poor electrical connections
- Malfunctioning engine control module (ECM)
- Issues with the transmission control module (TCM)
- Software glitches or programming errors
- Faulty ABS module
- Problems with the CAN bus communication system
Common misdiagnosis for U2420 U2420: Vehicle Speed Signal Communication Error
- Faulty vehicle speed sensor
- Wiring issues or damaged connectors
- Faulty ABS module
- Malfunctioning engine control module (ECM)
- Incorrect tire size or pressure
- Transmission issues
- Faulty instrument cluster
- Software glitches or updates needed in the vehicle’s control modules
Common Troubleshooting Steps
The OBD-II code U2420 indicates a “Vehicle Speed Signal Communication Error.” This code typically points to a problem with the communication between the vehicle’s modules regarding the vehicle speed signal. 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.
- Inspect Wiring and Connectors: Examine the wiring and connectors related to the vehicle speed sensor (VSS) and the modules that communicate the speed signal. Look for:
- Damaged or frayed wires
- Corroded or loose connectors
- Poor ground connections
- Test the Vehicle Speed Sensor (VSS): The VSS is responsible for sending speed data to the vehicle’s computer. Test the sensor for proper operation:
- Check the sensor’s resistance and output voltage using a multimeter.
- If the sensor is faulty, replace it.
- Check Module Communication: Use a scan tool to check if the modules (e.g., Engine Control Module (ECM), Transmission Control Module (TCM), etc.) are communicating properly.
- Look for any communication errors between modules.
- Inspect the ABS System: If your vehicle is equipped with an Anti-lock Braking System (ABS), check the ABS sensors and wiring, as they can also provide vehicle speed information.
- Check for Software Updates: Sometimes, a software update for the vehicle’s modules can resolve communication issues. Check with the manufacturer or a dealership for any available updates.
- Clear Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner.
- Take the vehicle for a test drive to see if the code reappears.
- 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.Additional Considerations
- Battery Voltage:** Ensure the vehicle’s battery is in good condition and fully charged, as low voltage can affect module communication.
- Environmental Factors:** Sometimes, environmental factors (like moisture or extreme temperatures) can affect sensor performance. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the U2420 code.