A common issue among Volkswagen, Audi, Group (VAG) car owners using VCDS (Vag-Com Diagnostic System) is the inability to clear fault codes, even after seemingly successful procedures. This article addresses the frustrating “Vcds Fault Wont Erase” problem, providing insights and potential solutions.
Understanding the “VCDS Fault Wont Erase” Problem
The scenario often unfolds as follows: A VCDS scan reveals fault codes in various modules. Attempting to clear these codes through the software prompts a message like: “The request to clear codes was not acknowledged by the engine control module.” Following the software’s suggestion to perform an OBD2 broadcast clear often results in a “Restarting session” message, yet the DTCs remain. Further attempts to manually clear codes using Mode 03 (Emission related fault codes) and Mode 07 (Pending emission related fault codes) may also yield no results, displaying “No fault code found.” This perplexing situation leaves many wondering what’s preventing the VCDS from erasing the faults.
Potential Causes and Solutions
Several factors can contribute to this issue:
Communication Errors:
- Faulty Cables or Connectors: A damaged or poorly connected VCDS cable or OBD2 port can disrupt communication between the software and the car’s modules. Solution: Inspect the cable and connectors for any visible damage. Ensure they are securely plugged in. Try a known good cable if possible.
- Low Battery Voltage: Insufficient battery voltage can hinder communication and prevent successful code clearing. Solution: Ensure the car’s battery is fully charged or connected to a charger during the process.
- Software or Driver Issues: Outdated VCDS software or incompatible drivers can cause communication problems. Solution: Update the VCDS software to the latest version and ensure the correct drivers are installed for the interface being used (e.g., HEX-NET).
Module-Specific Issues:
- Engine Control Module (ECM) Problems: The ECM plays a crucial role in clearing fault codes. Internal issues within the ECM can prevent it from acknowledging clear requests. Solution: Further diagnostics may be necessary to pinpoint the specific ECM problem. This may involve checking for ECM-specific trouble codes and consulting factory repair manuals.
- Immobilizer Issues: In some cases, an active immobilizer can block code clearing. Solution: Address any immobilizer-related issues first. This might involve key matching or addressing other immobilizer faults.
- Pending Fault Codes: Pending codes indicate a problem that hasn’t fully developed into a permanent fault. These codes might not be clearable immediately. Solution: Drive the vehicle under the conditions that triggered the pending code to see if it becomes a permanent fault. Then attempt clearing again.
Other Potential Problems:
- Aftermarket Modifications: Certain aftermarket modifications can interfere with the car’s diagnostic systems and prevent code clearing. Solution: Investigate any recent modifications that might be impacting the diagnostic process.
- Complex Fault Conditions: Sometimes, underlying issues causing the fault codes need to be resolved before the codes can be cleared. Solution: Perform a thorough diagnostic scan of all modules, addressing any detected faults in a logical order.
Conclusion
The inability to erase fault codes with VCDS can stem from various sources, ranging from simple communication errors to more complex module-specific problems. By systematically investigating these potential causes and applying the suggested solutions, you can increase your chances of successfully clearing the fault codes and resolving the underlying issues in your VAG vehicle. If problems persist, consult a qualified VAG technician for further assistance.
Example of a VCDS scan showing fault codes.
Location of the OBD2 port in a vehicle.
A typical VCDS cable used for diagnostics.
