*Important Note-Before starting the diagnosis process, verify that the ECM calibration is up to date. An outdated ECM calibration can lead to issues with sensors and modules.
- Inspect the DEF for contamination. When using a refractometer, a proper reading should be 32.5%.
- Verify the ECM calibration and ensure it is updated to the latest version.
- If quality is good, diagnose other DEF codes next.
TROUBLESHOOTING SHACK 