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Test Description

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

  1. 2:  This step determines if the condition is present. This test may take 5-10 minutes for the diagnostic to run.
  2. 4:  This step tests the HO2S signal and the low reference circuit for an high resistance. The HO2S voltage should go low.
  3. 8:  An exhaust leak 6-12 inches away from the HO2S can cause a DTC to set.
  4. 9:  Certain RTV silicone gasket materials release vapors that can contaminate the HO2S. 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 Values 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.
  1. Allow the engine to reach the normal operating temperature.
  2. Operate the vehicle within the parameters specified in Conditions for Running the DTC.
  3. Observe the diagnostic trouble code (DTC) information with a scan tool.
Did the DTC fail this ignition?		 - Go to Step 4  Go to Step 3 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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 
  1. Turn OFF the ignition.
  2. Disconnect the heated oxygen sensor (HO2S) harness connector.
  3. Connect a 3-ampere fused jumper wire between the signal circuit and the low reference circuit of the HO2S.
  4. Turn ON the ignition, with the engine OFF.
  5. Observe the HO2S 2 voltage parameter with a scan tool.
Is the voltage less than the specified value?		 20 mV Go to Step 8  Go to Step 5 
5
  1. Connect a 3-ampere fused jumper wire between the HO2S 2 signal circuit and a good ground.
  2. Observe the HO2S 2 voltage parameter with a scan tool.
Is the voltage less than the specified value?		 20 mV Go to Step 7  Go to Step 6 
6 Test the HO2S 2 signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 10 
7 Test the HO2S 2 low reference circuit for high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 10 
8  Inspect for an exhaust leak near the HO2S. 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 13  Go to Step 9 
9  Inspect or test for the following conditions:
Did you find and correct the condition?		 - Go to Step 13  Go to Step 11 
10 Test for shorted terminals and for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 12 
11 Replace the HO2S. Refer to Heated Oxygen Sensor Replacement - Sensor 2 .
Did you complete the replacement?		 - Go to Step 13  -
12 Replace the ECM. Refer to Engine Control Module Replacement .
Did you complete the replacement?		 - Go to Step 13  -
13
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 14 
14 Are there any DTCs that have not been diagnosed? - Go to Diagnostic Trouble Code (DTC) List System OK
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