How do you fix 2001 subaru with error p0661?

Error code P0661 on a 2001 Subaru typically indicates an issue with the intake manifold tuning valve (IMTV) or its circuit. To fix it, first, inspect the wiring and connectors for any damage or corrosion. If the wiring appears intact, test the IMTV motor for proper operation and replace it if necessary. Finally, clear the error code and take the vehicle for a test drive to ensure the issue is resolved.