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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 54 (Engine Controls And Fuel - 6.0L - DTC P0141 To DTC P0454) >> DTC P0172 or P0175 >> Test Description

Test Description

WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 7:  An EVAP canister that is saturated will cause a rich condition.
DTC P0172 or P0175

Step Action Values Yes No
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 Are any DTCs other than DTC P0172 or P0175 also set? - Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Step 3 
3
  1. Install a scan tool.
  2. Start and idle the engine at the normal operating temperature in Closed Loop.
  3. Record the long term fuel trim data.
  4. Turn OFF the engine.
  5. Turn ON ignition, with the engine OFF.
  6. Review the Freeze Frame/Failure Records and record the displayed data for this DTC.
Does the scan tool indicate that the long term fuel trim is less than the specified value?		 -13% Go to Step 4  Go to Diagnostic Aids
4
  1. Operate engine at idle.
  2. Observe HO2S parameters with a scan tool.
Does the scan tool indicate that the values are within the specified range and fluctuating?		 200-800 mV Go to Step 5  Go to Step 6 
5
  1. Turn OFF the engine.
  2. Visually and physically inspect the following items:
    • The evaporative emission (EVAP) lines and components for damage or blockage-Refer to Evaporative Emissions Hose Routing Diagram .
    • The inlet screen of the mass air flow (MAF) sensor for blockage
    • The vacuum hoses for splits, kinks, and proper connections-Refer to Emission Hose Routing Diagram .
    • The air intake duct for being collapsed or restricted
    • The air filter for being dirty or restricted
    • For objects blocking the throttle body
Did you find and correct the condition?		 - Go to Step 8  Go to Step 7 
6
  1. Turn OFF the engine.
  2. Inspect the heated oxygen sensor (HO2S) for proper installation.
  3. Inspect to ensure that the electrical connectors and the wires are secure and not contacting the exhaust system.
  4. Test for continuity between the signal circuit and the low reference circuit. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 8  Go to Fuel System Diagnosis
7  Inspect for the following:
Did you find and correct the condition?		 - Go to Step 8  Go to Symptoms - Engine Mechanical
8
IMPORTANT: After repairs, use the scan tool Fuel Trim Reset function to reset the Long Term Fuel Trim.
  1. Turn ON the ignition, with the engine OFF.
  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 2  Go to Step 9 
9 In order to ensure that the performance of the catalyst has not been affected by the fault that set this DTC, operate the vehicle within the conditions for running and setting DTC P0420 or P0430 and verify that P0420 or P0430 runs and passes. Refer to DTC P0420 or P0430 .
Does the DTC run and pass?		 - Go to Step 10  Go to DTC P0420 or P0430 
10 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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