Chevrolet Equinox Service Manual: Silicon Contamination of Heated Oxygen Sensors Caution Engine Control Engine Control Sensors O2 Sensors

Caution:Contamination of the oxygen sensor can result from the use ofan inappropriate RTV sealant (not oxygen sensor safe) or excessiveengine coolant or oil consumption. Remove the HO2S and visuallyinspect the portion of the sensor exposed to the exhaust stream inorder to check for contamination. If contaminated, the portion ofthe sensor exposed to the exhaust stream will have a white powderycoating. Silicon contamination causes a high but false HO2S signalvoltage (rich exhaust indication). The control module will thenreduce the amount of fuel delivered to the engine, causing a severedriveability problem. Eliminate the source of contamination beforereplacing the oxygen sensor.