Patent ID: 8382973

Claim:
A method for controlling a multi-gas sensor, the multi-gas sensor comprising an NO x sensor section; and an ammonia sensor section formed on an outer surface of the NO x sensor section, wherein the NO x sensor section includes a first pumping cell which has paired first electrodes provided on a first solid electrolyte body such that the paired first electrodes are located on both the interior and exterior of a first measurement chamber, respectively, and is adapted to pump oxygen into or out of a gas under measurement introduced into the first measurement chamber, and a second pumping cell which, has paired second electrodes provided on a second solid electrolyte body such that the paired second electrodes are located on both the interior and exterior of an NO x measurement chamber communicating with the first measurement chamber, respectively, and is configured such that a second pumping current flows between the paired second electrodes, the second pumping current corresponding to an NO x concentration of the gas under measurement having flowed into the NO x measurement chamber after adjustment of its oxygen concentration in the first measurement chamber; and the ammonia sensor section has a solid electrolyte body and at least a pair of electrodes formed on a side of the solid electrolyte body opposite the NO x sensor section and outputs an ammonia concentration output, wherein the solid electrolyte body of the ammonia sensor section is insulated from the NO x sensor section by an insulating layer, the method comprising calculating an oxygen concentration on the basis of a first pumping current flowing through the first pumping cell; and calculating a corrected ammonia concentration on the basis of the oxygen concentration and the ammonia concentration output of the ammonia sensor section.