2.3L Engine

Fig 1: Exhaust Gas Recirculation (EGR) System Diagram (2.3L)

Courtesy of MAZDA MOTORS CORP.

The exhaust gas recirculation (EGR) system returns a small amount of exhaust gas into the intake manifold. This reduces the overall combustion temperature. Cooler combustion temperatures provide a significant reduction of the oxides of nitrogen (NOx) in the exhaust emissions.
The 2.3L engine incorporates a stepper motor-controlled EGR valve which receives its signal from the powertrain control module (PCM). Engine coolant is used to cool the EGR valve. The EGR valve and stepper motor are serviced as an assembly.