The isolated enhancement effects of O2(a1Δ g) on lifted flame propagation was investigated experimentally and numerically at reduced pressures. Through quantitative absorption measurements it was found that O2(a1Δg) was produced in excess of 5500 ppm and was isolated from all other plasma-produced species via NO injection before transport to the C2H4 lifted flame. Clear trends of increased flame propagation enhancement with increased O2(a1Δg) concentrations were found, with up to 3% enhancement observed. Numerical simulations with the current O 2(a1Δg) kinetic mechanisms, containing only hydrogen species, showed significant trend deviations from the experimental results, indicating errors in the kinetics. The inclusion of new estimated temperature dependent rates of O2(a1Δg) collisional quenching by hydrocarbon species mitigated the deviation, but require validation. Flow reactor experiments with conditions mimicking the early stages of the flame showed that low temperature oxidation of C 2H4 in the range of 583 K to 728 K mimicked the low temperature kinetic pathways of enhancement through NO sensitization with OH production. Therefore the inclusion of O2(a1Δ g) quenching by hydrocarbon species, as well as low temperature chemistry is necessary for accurate modeling of the enhancement pathways by O2(a1Δg).