High-resolution emission spectroscopy of rovibrational Δv=2 sequence bands is carried out from a low-pressure discharge through pure CO gas. The effect of rare gases on the production of the Δv=2 sequence bands is also studied. The v’→(v’-2) sequence bands up to v’= 17 are observed. Bands involving 8≤v’≤17 in the Δv=2 sequence are reported for the first time. The 16-14 and 17-15 bands could be observed only in the presence of xenon as a buffer gas. Accurate molecular constants (T, B, D, H) for different vibrational states of the ground electronic state of ¹²C¹⁶O are determined from a global fit.