Oxygen Sensor: Description and Operation

Fig. 8 Exhaust gas oxygen (EGO) sensor:

The exhaust gas oxygen sensor supplies the ECA with a signal which indicates either a rich or lean condition during engine operation. The sensor is threaded into the center of the exhaust manifold on 4-140 and 6-300 engines, threaded into the rear of left and right exhaust manifold assemblies on V6-171 engine or threaded into the rear right exhaust manifold assembly on V8-302 and 351 engine, Fig. 8.