EGR Boost Control Solenoid: Description and Operation

EGR Boost Check Solenoid:

PURPOSE
An EGR Boost Check (EGRCHK) solenoid is used to control when the EGR boost sensor is checked. It is a three way solenoid valve that switches between atmospheric pressure and EGR pressure. The EGRCHK solenoid is used only for the EGR system monitor.

OPERATION
At certain times in a drive cycle, the Powertrain Control Module (PCM) will command the EGRCHK solenoid to open and allow EGR pressure, or the drop in manifold vacuum due to EGR flow, to pass to the EGRB sensor. Using this strategy the PCM can monitor the EGR system to ensure that the system is functioning properly.