DB21 - Check EGR Valve Operation

- Key "OFF".

- Vacuum hose disconnected at EGR valve.

- Vacuum pump connected to EGR valve.

- Clear continuous memory. Clearing Diagnostic Trouble Codes

- Start engine.

- Slowly apply 34 kPa (10 in Hg) vacuum to the EGR valve and hold for at least two minutes.

- Does engine idle rough or stall?

Yes -- Turn engine "OFF". Go to DB22. DB22 - Check For Continuous Memory Code 326

No -- Turn engine "OFF". Remove vacuum pump. Reconnect vacuum hose. Refer to Emission Control Systems for EGR valve diagnosis.