Hello everyone I'm having an issue with my 96 328ic with sas. Initially I got the codes p1423 and p1421. I replaced the air pump and p1423 went away but I still get the p1421 code. I checked the valve and it does open at a cold start and close after a minute or so.. I put the valve under vacuum and it allows airflow once vacuum is removed it does not.. now could this valve still be bad and cause this code to pop up? Would really appreciate any help since im trying to pass smog.. thanks