5 wires come out of the wall. One (the yellow) was tied off and not connected to the 890121. The blue wire was connected to C, the green to G, the W to White and the red to Y.

The RTH230B has RH, RC,W, Y and G. connection positions. What wires go where?

Can not locate this part number you provided. (890121)

Please list the brand name and correct part number so I can look this up.