The passages for the Exhaust Gas Recirculation (EGR) system can become restricted or clogged causing the Check Engine Light to illuminate. The EGR valve will need to be inspected and the passages cleaned.
Car Problem Reports
Mazda Millenia Check Engine Light Due to Restricted EGR System
Mazda Millenia Problem
Average Mileage: 94,720 mi (13,100 mi - 165,000 mi)
Visitor, 1998 Mazda Millenia, 165,000 mi
check engine light comes on and ,Scan could not figure out what error code is that light for ....
Visitor, 1998 Mazda Millenia, 103,000 mi
check engine light on, cleaned egr valve cleaned. Cured
Visitor, 2002 Mazda Millenia, 55,000 mi
Had lines cleaned several times still comes back within the week.