Comcast Cable set-top boxes are made to coordinate local time based on global positioning settings coded into the unit. Therefore, any change in the time display on the cable box, like daylight savings time, for example, is automatically adjusted based on satellite position. However, there are occasions where diagnostic issues with a particular box cause it to display an incorrect time. In these cases, the time can be changed by resetting the factory settings on the box.
Press the "Power" button on the cable box and immediately press "Select." This will enable the diagnostic mode. You will see "d01" displayed on the LCD of the box, indicating it is in that mode.
Press the channel or cursor "Up/Down" arrows to scroll through the diagnostic codes on the display until you reach "00B" (which is the code for the GPS time settings); then press "Select." This action will reset the time or display an error code. If an error code is displayed, you may need to have the cable box checked by a Comcast technician.
Press the cursor "Left/Right" arrows to select "E" on the main menu or press "Power" to exit the diagnostic mode.