Selected 8 keV energy cations (O+(4S), CN+(1Sigma+), F+(3P) and Ar2+(3P)) were allowed to undergo single-electron-capture reactions with CO2 molecules, and the fast products, anionized where necessary, were translational-energy analysed. The spectra indicated that, in addition to the X 2Pig, A 2Piu, B 2Sigmag+, C 2Sigmag+, and 12Piu states, certain other states of CO2+ were populated, the latter having vertical ionization energies of 21.9+or-0.4 eV, 23.4+or-0.3 eV, 24.3+or-0.4 eV and 26.3+or-0.3 eV. From documented ab initio calculations these are likely to be the spectroscopically hidden diexcited states 4Piu, 2Phiu, 4Sigmag- (or possibly 2Sigmag-) and 1 2Sigmag+ (or possibly 2Deltag or 1 2Pig), respectively.