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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1569 (Engine Controls And Fuel - 3.5L (L66) - DTC P0223 To DTC P0499) >> DTC P0420 or P0430 >> Test Description

Test Description

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 1:  The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and to store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. 3:  This step verifies whether the malfunction is presently occurring.
  3. 8:  In order to avoid repeated replacement of the catalytic converter, inspect for the cause of the converter failure and repair as necessary. Refer to Diagnostic Aids.
DTC P0420 or P0430

Step Action Value(s) Yes No
1  Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 Check any for any heated oxygen sensor DTCs and diagnose those DTCs first.
Are there any heated oxygen sensor DTCs set?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Step 3 
3 
  1. Install a scan tool.
  2. Start the engine.
  3. Run the engine until the normal operating temperature is reached.
  4. Verify that the engine is operating in Closed Loop.
  5. Run the engine at the specified value for 3 minutes.
  6. Monitor the fuel control HO2S and the catalyst monitor heated oxygen sensors (HO2S) signals of the suspect converter on the scan tool.
Is the catalyst monitoring HO2S signal as active as the fuel control HO2S signal?		 2,500-3,000 RPM Go to Step 5  Go to Step 4 
4
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Clear the DTCs with a scan tool.
  3. Turn OFF the ignition for 30 seconds.
  4. Start the engine.
  5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 5  Go to Diagnostic Aids In This Test
5
  1. Visually and physically inspect the 3-way catalytic converter (TWC) for the following concerns:
    • Dents or physical damage
    • Severe discoloration caused by excessive temperatures
    • Holes or punctures
    • Internal rattles caused by a damaged catalyst element
  2. Verify that the TWC is a high quality part that meets the OEM specifications.
Did you find a problem?		 - Go to Step 8  Go to Step 6 
6
  1. Visually and physically inspect the exhaust system for any of the following conditions:
    • Exhaust Leaks-Refer to Exhaust Leakage .

    • Physical damage
    • Loose or missing hardware
  2. Repair as necessary.
Was a repair necessary?		 - Go to Step 9  Go to Step 7 
7
  1. Visually and physically inspect the catalyst monitor HO2S of the suspect converter for the following conditions:
    • The pigtail and wiring harness making contact with exhaust pipe
    • A loose HO2S
    • Any road damage
  2. Repair as necessary.
Was a repair necessary?		 - Go to Step 9  Go to Step 8 
8 
IMPORTANT: Locate and repair the cause of the TWC converter failure before installing the replacement converter.
Replace the TWC.Is the action complete?		 - Go to Step 10  -
9
  1. Start the engine.
  2. Run the engine until the normal operating temperature is reached.
  3. Verify that the engine is operating in Closed Loop.
  4. Run the engine at the specified value for 3 minutes.
  5. Monitor the fuel control HO2S and the catalyst monitor HO2S signals of the suspect converter on the scan tool.
Is the catalyst monitoring HO2S signal as active as the fuel control HO2S signal?		 2,500-3,000 RPM Go to Diagnostic Aids In This Test Go to Step 10 
10
  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. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 11 
11 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
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