Resetting Your 2017 Subaru WRX VVT System Without ECM Replacement: The Scan Tool Solution

For owners and technicians dealing with newer Subaru models, particularly the 2017 Subaru WRX, a frustrating issue has emerged concerning the Variable Valve Timing (VVT) system. Data related to the VVT system can be stored in the EEPROM, and traditionally, clearing this data has been a costly affair, often requiring Electronic Control Module (ECM) replacement or complex EEPROM work. Subaru Technical Service Bulletin 02-163-16r even indicates ECM replacement as the necessary fix for this problem.

However, there’s now a more efficient and cost-effective solution that bypasses ECM replacement and EEPROM manipulation: utilizing a scan tool. This method allows you to reset the VVT system data directly, saving both time and money.

Here’s how you can reset your 2017 Subaru WRX VVT system using a scan tool:

Step-by-Step Guide to Resetting VVT Data:

1. Key Off & Inspection Fuse: Begin with the ignition key in the OFF position. Locate the underhood fuse panel and install the designated inspection mode fuse. The exact location of this fuse can vary depending on the year of your WRX, so consult your service information for the precise location.
2. Key On & Fan Cycling: Turn the ignition key to the ON position. You may hear the cooling fans start to cycle – this is a normal part of the process.
3. Scan Tool Connection & Special Functions: Connect a compatible scan tool (like Launch or Autel – other tools may also work) to your Subaru WRX’s ECM. Navigate to the “special functions” menu within your scan tool interface.
4. Enter Test Mode: Look for an option within the special functions menu to change or activate “test mode”. Select this option. You should observe the check engine light beginning to flash, indicating test mode is active.
5. Clear Diagnostic Trouble Codes (DTCs): While test mode is active and the check engine light is flashing, go back to the diagnostic menu and clear any stored trouble codes (DTCs).
6. Key Off & Fuse Removal: Turn the ignition key back to the OFF position. Remove the inspection fuse from the underhood fuse panel.
7. Verification: Turn the ignition key back to the ON position and use your scan tool to verify that the VVT system values have been successfully reset.

This procedure has been successfully tested and verified on a range of Subaru models, including 2015, 2016, and 2019 WRX vehicles, demonstrating its effectiveness in resetting VVT values, whether they are within or outside of the expected range.

This innovative approach was inspired by Robbie Magill’s work on resetting the learning misfire profile on timing belt engines. While initial attempts to apply a similar method to VVT systems were unsuccessful, collaboration and further investigation by Rob Dotterer and Joe Bonino led to the crucial discovery of activating test mode via the scan tool, which ultimately unlocked this efficient reset procedure. This scan tool method provides a valuable alternative to ECM replacement for resetting the VVT system in your 2017 Subaru WRX and similar models.