Need to pass NYS inspection- EGR problem -although it functions-
P0401 says there’s insufficient flow.
Even though the valve opens if the passage ways are clogged with carbon the gasses won’t flow properly.
Probably a buildup of deposits between the valve and the intake manifold, or in the manifold.
^ What circuitsmith said. Take it apart, clean it out, clear the code, and see if the code returns. If the code does return even though all of the passages have been cleaned out then you have to look at the control side of the EGR system. There’s probably a sensor and a vacuum solenoid. Both of those need to be checked if the clean-up doesn’t do it.