How to know when EGR valve is working at all??

I have 01, firebird, v6, read the code, said egr valve is bad. bought the new one, changed it, it was working fine for a week. Then, code come back, it seem like a new egr doesn't work at all, no sound or getting hot, pipe is cleaned . code said egr sensor running low. Does normally, egr suppose to get hot when it's working? How to check if it working at all?How to know when EGR valve is working at all??
Too much EGR flow at idle, cruise, or cold operation may cause any of the following conditions to occur:



* The engine stalls after cold start

* The engine stalls during closed throttle conditions

* The vehicle surges during cruise

* Rough idle

* DTC P0300-Misfire detected



Too little or a lack of EGR flow may allow combustion temperatures to get too high. This could cause the following symptoms:



* Spark knock or detonation

* Engine overheating

* Emission test failure

* DTC P0401

* Poor fuel economy



EGR flow diagnosis is included in the DTC P0401 diagnostic table. Pintle position error diagnosis is covered in DTC P1406. If EGR DTCs P0401 and/or P1406 are encountered, refer to Diagnostic Trouble Code (DTC) List for diagnosis.



So..What code was before you replaced EGR valve????How to know when EGR valve is working at all??
Check vacuum hose that go to EGR solenoid,they may be cracked and leaking vacuum.