Circuit Description

The EGR system recirculates exhaust gas through intake system to reduce combustion temperature and NOx emissions. The amount of EGR valve opening is regulated by the EGR vacuum modulator according to engine load. Vacuum source to valve is controlled by the Vacuum Switching Valve (VSV), which is controlled by ECM.

The EGR valve is closed (VSV on) under the following conditions:

• Engine is not warmed up.
• Vehicle under deceleration.
• Light engine load.
• Engine racing.

Code is set when EGR temperature sensor value is high with engine not yet at normal operating temperature. Possible causes are:

• EGR valve stuck open.
• EGR Vacuum Switching Valve (VSV).
• EGR VSV open circuit.
• EGR temperature sensor short circuit.
• ECM.