Camry CNG Models, Camry Gasoline Models With Calif. Emissions, Camry Solara Calif. Emission Vehicles & RAV4 Calif. Emission Vehicles

Heated A/F sensor is mounted on exhaust manifold above catalytic converter. If problem exists in A/F sensor, heater or wiring circuit, a Diagnostic Trouble Code (DTC) may be stored in Engine Control Module (ECM). See SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article for retrieving and servicing of DTCs.
To test heater resistance on A/F sensor, disconnect electrical connector for A/F sensor. Using ohmmeter, check resistance between +B and HT terminals on electrical connector. See Fig 1 and Fig 2 . Replace A/F sensor if resistance is not.8-1.4 ohms at 68°F (20°C).

Fig 1: Testing Heater On A/F Sensor (Camry CNG Models, Camry Gasoline Models With Calif. Emissions & Camry Solara Calif. Emission Vehicles)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Testing Heater On A/F Sensor (RAV4 Calif. Emission Vehicles)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002