Exhaust Gas Recirculation: Description and Operation

The Exhaust Gas Recirculation (EGR) system reduces oxides of nitrogen (NOx), by allowing a specified amount of hot exhaust gas to mix with the incoming air/fuel mixture. The addition of oxygen depleted exhaust gas lowers combustion temperatures reducing the amount of NOx produced during combustion.

California vehicles are supplied with an on-board diagnostic system for the EGR system. This system has a solenoid that is placed in the vacuum signal line to the EGR valve. This solenoid disables the EGR system during select engine/driving conditions, so the PCM can perform a system diagnostic check. The PCM checks the entire EGR system for failures, and if the system check shows a failure, the CHECK Engine lamp in the instrument panel will illuminate indicating that immediate service is required.

Electric EGR Transducer (EET):

EGR Mounting:

CONTROL VALVE AND ELECTRONIC TRANSDUCER

This system has an electronically controlled vacuum solenoid that is an integral part of the Electronic EGR Transducer (EET). The electronic portion of the solenoid receives its electronic signal from the PCM. The solenoid uses this signal to regulate the amount of vacuum supplied to the EGR transducer. Vacuum is supplied to the EET by a ported vacuum signal from the throttle body. The transducer measures the amount of exhaust gas backpressure on the exhaust side of the EGR valve and varies the amount of vacuum supplied to the EGR valve. The transducer uses this backpressure signal to supply the correct amount of vacuum to the EGR valve depending on engine load conditions.