Toyota Repair Problems? Ask a Mechanic for Answers ASAP
Actually, in my experience, the most common fault item associated with the P0401 is a faulty VSV for EGR. Double check all the vacuum lines to/from this VSV are good. If the visual check is good, suspect a faulty VSV for EGR. It's located on the side of the engine closest to the firewall, about mid-way down. Best access is through the passenger's side wheel well.