Exhaust gas sensing system and method for determining concentrations of exhaust gas constituents

3 2 x x 2 3 x 3 2 An exhaust gas sensing system and a method for determining concentrations of exhaust gas constituents are provided. The exhaust gas sensing system includes a NHsensing cell, a NOsensing cell, a NOpumping cell, and a current sensor that detects an electrical current flowing through the NOpumping cell. A computer determines a NOconcentration value, a NHconcentration value, a NO concentration value, and a NOconcentration value based on signals from the NHsensing cell, the NOsensing cell, and the current sensor.