Air Fuel Ratio (A/F) Sensor On-Vehicle Inspection: Heater

Disconnect A/F sensor connector.
Using ohmmeter, measure resistance of sensor heater between terminals "VB" and "GND" at sensor connector. If found faulty, replace A/F sensor.
NOTE: Temperature of sensor affects resistance value largely. Make sure that sensor heater is at correct temperature.

A/F sensor heater resistance

2 - 3 Ω at 20 °C (68 °F)

Fig 1: Identifying A/F Sensor Connector - Terminal Side
Courtesy of SUZUKI OF AMERICA CORP.
Connect A/F sensor connector securely.