NEMCA known for the increasing the catalytic activity/selectivity of the gas exposed electrodes was investigated for the potentiometric zirconia oxygen sensor activation. Electrochemical promotion of O 2-sensors with Pt-cermet electrodes aged in the field was significant with up to 5 times in the impedance reduction. Stability test on the NEMCA activated O 2-sensors was showing just a minor impedance increase. Sensor response time was reduced by NEMCA effect by ~5-10% with up to 3 times signal noise reduction on the aged O 2-sensors.