The vacuum ultraviolet (VUV) pulsed field ionization-photoelectron (PFI-PE) spectra for CO2 have been measured in the energy range of 17.2-19.0 eV, showing complex vibronic structures for the CO2+(A (2)Pi (u) and B (2)Sigma (+)(u)) states. The PFI-PE spectra for CO2+(A (2)Pi (u) and B (2)Sigma (+)(u)) are dominated by the upsilon (+)(1) (symmetric stretching) vibrational progressions, and weak bands due to excitation of both even and odd quanta of the upsilon (+)(2) (bending) and upsilon (+)(3) (antisymmetric stretching) modes are observed in the VUV-PFI-PE spectra. The simulation of rotational contours resolved in the PFI-PE vibronic bands associated with excitation to CO2+(A (2)Pi (3/2,1/2u);upsilon (+)(1)=0-5,upsilon (+)(2)=0,upsilon (+)(3)=0) and CO2+(B (2)Sigma (+)(u);0,0,0) has yielded accurate ionization energies for the formation of these states from CO2(X (1)Sigma (+)(g)). Three-dimensional potential energy functions (PEFs) for CO2+(B (2)Sigma (+)(u)) have also been generated theoretically using the complete active space self-consistent field and internally contracted multireference configuration interaction methods. Based on these PEFs, vibrational energy levels for CO2+(B (2)Sigma (+)(u)), together with the Franck-Condon factors for their formation from CO2(X (1)Sigma (+)(g)), have been calculated. With the guide of these theoretical predictions, the vibrational bands resolved in the PFI-PE spectrum for CO2+(B (2)Sigma (+)(u)) have been satisfactorily assigned. This assignment reveals the nature of many vibrational PFI-PE bands as originated from anharmonic resonance interactions and members of Fermi polyads.