P0405 EGR Sensor A Circuit Low

Hi,

I have a Chevy Tahoe 1999
At the emission test I got an error "P0405 EGR Sensor A Circuit Low"
There is any one who can tell me what should I do to fix this problem.
I replaced the EGR valve and the message is it still coming.

Thanks in advance. My E-mail address is: [email protected].