A frequent issue encountered when using VCDS (Vag-Com Diagnostic System) is the inability to clear fault codes, even after seemingly successful procedures. This article explores potential causes and solutions when a VCDS fault won’t erase. We’ll analyze a specific case study of a 2012 VW Golf to illustrate common problems and troubleshooting steps.
Understanding the “VCDS Fault Wont Erase” Problem
The scenario often unfolds as follows: a fault code scan reveals errors, the user attempts to clear them via VCDS, receives a confirmation message, but the codes persist. This frustrating situation can be caused by various factors, from simple communication errors to more complex module malfunctions. The case study below highlights a typical instance of this problem.
Case Study: 2012 VW Golf – VCDS Fault Code Clearing Failure
A 2012 VW Golf owner used VCDS 22.10.0.1 to scan for faults. Despite no Malfunction Indicator Lamp (MIL) illuminated, the scan revealed several fault codes across multiple modules, including the engine, central electrics, airbags, and steering assist. Attempts to clear the codes resulted in VCDS reporting: “The request to clear codes was not acknowledged by the engine control module.” Following the software prompt to proceed with an OBD2 broadcast clear also failed, with the session restarting and DTCs remaining. Manual checks in OBD2 Mode 03 (Emission related fault codes) and Mode 07 (Pending emission related fault codes) showed no faults.
Example of VCDS Scan Showing Fault Codes
The VCDS scan revealed a multitude of communication errors (U codes) between various modules, notably:
- U0164: No Communication with HVAC Control Module (J301)
- U0155: No Communication with Instrument Cluster
- U0146: No Communication with Diagnostic Gateway
- U0212: No Communication with Steering Column Control Module
Additionally, faults related to the ABS module, light switch, lamps, and the radio were logged. Crucially, the engine module (Address 01) reported:
- P1570: Engine Start Blocked by Immobilizer
- Several U codes indicating communication issues with other modules.
Potential Causes and Solutions
When a VCDS fault won’t erase, several potential causes should be investigated:
1. Communication Issues: The prevalence of U codes in the Golf’s scan suggests communication problems between modules. A faulty CAN bus or wiring harness could prevent proper communication and hinder code clearing. Inspecting wiring harnesses for damage, corrosion, or loose connections is crucial.
2. Module Malfunctions: A malfunctioning module may not respond to clear code requests. The “Engine Start Blocked by Immobilizer” (P1570) error could indicate a serious issue with the engine control module or immobilizer system, potentially requiring specialized repair or replacement.
3. Low Battery Voltage: While the VCDS log shows stable battery voltage during the scan, a low voltage condition during previous driving cycles could have contributed to logged faults. Ensure the battery is fully charged and tested for proper operation.
4. Software or Hardware Issues: Although less likely, outdated VCDS software or a faulty interface cable could contribute to communication problems. Using the latest version of VCDS and a known-good cable is recommended.
5. Pending Codes: Some fault codes may be pending and require specific driving conditions to be met before they can be cleared. Consult the vehicle’s repair manual for specific code clearing procedures.
Conclusion
Successfully resolving a “VCDS fault won’t erase” issue requires systematic troubleshooting. Start by addressing communication issues, verifying module functionality, and ensuring adequate battery voltage. If problems persist, consider seeking professional assistance from a qualified automotive technician experienced with VCDS and Volkswagen diagnostics. A thorough diagnosis is crucial to identify the root cause and prevent recurring problems.
