Exhaust Gas Recirculation: Description and Operation

Exhaust Gas Recirculation (EGR) System
The EGR system:
- returns a small amount of exhaust gas into the engine for recombustion.
- reduces the overall combustion temperature and
- provides a significant reduction of oxides of nitrogen (NOx).

The EGR valve:
- is electronically controlled by the powertrain control module (PCM) (12A650).
- controls the vacuum to the EGR valve.

The EGR valve:
- is connected to the exhaust manifold by the EGR valve to exhaust manifold tube.
- controls recirculated exhaust gas flow to the intake manifold.
- monitors the flow of recirculated exhaust gases through the EGR valve to exhaust manifold tube.
- returns a signal to the powertrain control module.

The amount of recirculated exhaust gas depends upon:
- engine rpm.
- intake manifold vacuum.
- exhaust back pressure.
- engine coolant temperature.
- throttle position.

The vehicle emission control information (VECI) decal:
- is located on the hood.
- lists the exhaust emission control system information.