Heated Oxygen Sensor

Two heated oxygen sensors are used. A heated oxygen sensor is used on exhaust pipe in front of front catalytic converter and on exhaust pipe behind rear catalytic converter.
If problem exists with heated oxygen sensor, a diagnostic trouble code will be stored in Engine Control Module (ECM). For diagnostic trouble code diagnosis, see TESTS W/CODES article.
To test the heater on the heated oxygen sensor, disconnect electrical connector from appropriate heated oxygen sensor and note heated oxygen sensor terminals. See Fig 1.
Using ohmmeter, check resistance between heated oxygen sensor terminals +B and HT. See Fig 1. Replace heated oxygen sensor if resistance is not 11-16 ohms at 68°F (20°C).

Fig 1: Testing Heated Oxygen Sensor