Test Description

The numbers below refer to the step numbers on the diagnostic table.

2: This step determines if the condition is present. This test may take 5-10 minutes for the diagnostic to run.
4: An exhaust leak 6-12 inches away from the O2S can cause a DTC to set.
5: Certain RTV silicone gasket materials release vapors that can contaminate the O2S. Silicone in the fuel can also cause silicone contamination. If the sensors appear contaminated by silicone, and if all the silicone sealant is a non-silicone base, advise the customer to try a different fuel company. A missing fuel filler restrictor indicates that the customer may have used leaded fuel.

Step	Action	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Engine Controls?	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	IMPORTANT: If any other DTCs are set, refer to those DTCs before proceeding with this diagnostic table. Allow the engine to reach the normal operating temperature. Operate the vehicle within the parameters specified in Conditions for Running the DTC. Observe the diagnostic trouble code (DTC) information with a scan tool. Does the DTC fail this ignition?	Go to Step 4	Go to Step 3
3	Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. Did the DTC fail this ignition?	Go to Step 4	Go to Intermittent Conditions
4	Inspect for an exhaust leak near the O2S. Refer to Symptoms - Engine Exhaust . After you inspect the exhaust system, return to this diagnostic. Did you find and correct the condition?	Go to Step 7	Go to Step 5
5	Inspect or test for the following conditions: The O2S is securely installed. Inspect for corrosion on the O2S terminals. Inspect the terminal tension at the O2S and at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Inspect the O2S wiring for damage. Refer to Wiring Repairs . Fuel that is contaminated. Inspect for the correct RTV sealant. Inspect for engine oil consumption. Refer to Oil Leak Diagnosis . Inspect for engine coolant consumption. Refer to Loss of Coolant . Did you find and correct the condition?	Go to Step 7	Go to Step 6
6	Replace the O2S. Refer to Oxygen Sensor Replacement . Did you complete the replacement?	Go to Step 7	-
7	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. Did the DTC fail this ignition?	Go to Step 2	Go to Step 8
8	Are there any DTCs that have not been diagnosed?	Go to Diagnostic Trouble Code (DTC) List	System OK