Sold and Guanranteed By GlobalSourceAMZ Only Brand: ISUMO The EGR Vacuum Modulator Valve controls the amount and frequency of vacuum sent to the EGR Valve When not replaced, the towers will oxidize or corrode creating a high secondary resistance which can result in reduced mileage, CEL, catalytic converter failure or a failed emissions test Designed to meet or exceed OE specifications in form and materials.