Monitor Description

Fig 1: A/F Sensor Circuit Slow Response Graphical Representation (Bank 1 Sensor 1)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

The output voltage of the A/F sensor varies in proportion to the air-fuel ratio. Based on these voltage variations, the ECM determines whether the actual air-fuel ratio is rich or lean, and makes adjustments to bring it close to the stoichiometric level. In addition, the ECM checks the fuel injection volume compensation value to determine whether the A/F sensor response time is normal or slow. The ECM calculates the ratio of the variations in both the A/F sensor output voltage and the fuel trim value.