A blown OBD II fuse (#43, 5A) caused a cheap scan tool to initially show no errors after replacement and a test drive confirmed working odometers. However, using a PASoft scan tool subsequently resulted in a “No Device” message and loss of trip odometer and clock functionality, despite fuse #43 remaining intact. The scan tool still powered up after resetting the odometer. The vehicle, a 2005 BMW 330ci, uses a Duralast Gold Battery (H7-DLG) from AutoZone with 790 CCA and 140 reserve minutes, matching AutoZone’s specifications for the model year. Further diagnostics are delayed due to a damaged USB interface on the PASoft dongle. The question remains whether the AutoZone scan tool can reliably read the odometer in this situation. While initial tests were positive, the subsequent failure raises concerns about the tool’s consistency and ability to communicate with the vehicle’s computer system.
AutoZone Scan Tool Functionality and Odometer Reading
Generally, most OBD II scan tools, including those sold at AutoZone, can read the vehicle’s odometer. This data is typically part of the standard diagnostic information accessible through the OBD II port. However, several factors can affect a scan tool’s ability to retrieve this information:
- Communication Errors: Issues with the vehicle’s electrical system, like a blown fuse or faulty wiring, can disrupt communication between the scan tool and the car’s computer, preventing data retrieval. The initial success followed by failure in this case suggests potential intermittent communication problems.
- Scan Tool Compatibility: While most scan tools adhere to OBD II standards, some advanced features or specific data points might not be accessible with all tools. The cheaper scan tool worked initially, but the more advanced PASoft tool encountered issues, indicating potential compatibility problems.
- Vehicle Specific Issues: Certain car models, particularly older ones, might have proprietary protocols or non-standard implementations of OBD II, making it difficult for some scan tools to access all data.
Troubleshooting Odometer Reading Problems
If an AutoZone scan tool isn’t displaying the odometer reading, consider these troubleshooting steps:
- Check Fuse #43: Even with a continuity test, ensure the fuse is properly seated and functioning. Try replacing it again with a new fuse.
- Inspect OBD II Port: Examine the port for any damage, debris, or loose connections. Clean the port with compressed air if necessary.
- Test with a Different Scan Tool: Using another scan tool, preferably a higher-end model or one specifically designed for BMWs, can help determine if the issue is with the tool or the vehicle.
- Check Battery Voltage: A weak battery can cause erratic behavior in the car’s electrical system and interfere with scan tool communication. Verify the battery voltage and ensure it meets the manufacturer’s specifications. The new battery in this case should rule out this possibility, but it’s always worth double-checking.
- Consult a Professional: If the problem persists, a qualified mechanic can diagnose and address any underlying issues with the vehicle’s electrical system or communication protocols.
Conclusion
While AutoZone scan tools are generally capable of reading odometer data, various factors can interfere with this functionality. This case highlights the importance of thorough troubleshooting, including checking fuses, the OBD II port, and using different scan tools to isolate the problem. If simple solutions don’t work, seeking professional help is recommended. The damaged PASoft dongle prevents further diagnostics, but resolving the underlying communication issue is crucial for reliable data retrieval and vehicle maintenance.
