Evaporative Purge System Monitoring

Evaporative Purge System Flow Check is performed by the EMS2000 when the oxygen sensor control and purging is active. When the Evaporative Emission Valve is open the EMS2000 detects a rich/lean shift as monitored by the oxygen sensors indicating the valve is functioning properly.

If the EMS2000 does not detect a rich/lean shift, a second step is performed when the vehicle is stationary and the engine is at idle speed. The EMS2000 opens and closes the valve (abruptly) several times and monitors the engine rpm for changes. If there are no changes, a fault code will be set.

The purge valve will also be activated (opened) towards the end of the LDP test cycle. The EMS2000 has to see the reed switch frequency increase when the purge valve opens. If the frequency does not increase, the EMS2000 sets a fault for the purge system.