EGR System Description

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.

4.0L Engine 

Fig 2: Exhaust Gas Recirculation (EGR) System Diagram (4.0L)

Courtesy of MAZDA MOTORS CORP.

• The 4.0L engine, the PCM controls the EGR vacuum regulator solenoid. The EGR vacuum regulator solenoid controls the vacuum to the EGR valve. When the EGR valve opens, exhaust gas flows to the intake manifold to be returned to the combustion cycle. The differential pressure feedback EGR system monitors the flow and returns a signal to the PCM.