AIR/FUEL SENSOR Toyota Prius I facelift

AIR/FUEL SENSOR

Note. Air/Fuel (A/F) sensor may also be referred to as Air/Fuel (A/F) ratio sensor.

Scheme 126

1. 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 TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article for retrieving of DTCs.
2. 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. (Scheme 126) Replace A/F sensor if resistance is not.8-1.4 ohms at 68°F (20°C).

Scheme 127

Scheme 128

1. Two heated A/F sensors are used. Heated A/F sensors are mounted on exhaust manifold above catalytic converters. A/F sensor for cylinders No. 1 and 4 is referred to as bank No. 1 sensor No. 1. A/F sensor for cylinders No. 2 and 3 is referred to as bank No. 2 sensor No. 1. 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 TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article for retrieving of DTCs.
2. 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. (Scheme 127)and (Scheme 128). Replace A/F sensor if resistance is not within specification. See «A/F SENSOR HEATER RESISTANCE»(ref-63407-S38773748322000122200000) table. A/F SENSOR HEATER RESISTANCE Application & Temperature Ohms Highlander 68°F (20°C) 1.8-3.4 932°F (500°C) 5.0-7.5 RAV4 68°F (20°C).8-1.4 1472°F (800°C) 1.8-3.2

Scheme 129

1. Heated A/F sensor is mounted on exhaust pipe in front of 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 TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article for retrieving of DTCs.
2. 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. (Scheme 129) Replace A/F sensor if resistance is not.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C).