Diagnostic Aids

WARNING: This page is about a different variant/trim than selected.

Test for a contaminated oxygen sensor. Silicone and other contaminants can cause the oxygen sensor to provide false exhaust oxygen content readings. If contamination is found, determine the cause and correct the condition before replacing the HO2S.
The scan tool output control feature, Fuel Injector Modification, can be used at idle to check the oxygen sensor performance. Commanding the Fuel Injector Modification Commanded State to 25 percent should cause the HO2S 1 voltage to decrease to less than 3 volts. Changing the Fuel Injector Modification Commanded State to -12 percent should cause the HO2S 1 voltage to increase to greater than 3.35 volts. An oxygen sensor that fails to respond accordingly may be faulty or contaminated. When performing the Fuel Injector Modification with the scan tool, the Loop Status will remain Open Loop and the Short Term FT will be fixed at 0 percent.
Test the HO2S 1 for water intrusion into the wiring harness and the sensor housing. Water can create a short to voltage in the HO2S signal circuit causing a false lean indication.