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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1857 (Engine Controls And Fuel - 3.5L (L66) - DTC P0030 To DTC P0222) >> DTC P0139 or P0159 >> 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 on the diagnostic table.

  1. 2:  The engine must be at the normal operating temperature before performing this test.
  2. 4:  If the scan tool indicates the HO2S voltage goes below 100 mV, this indicates the HO2S circuits and the PCM are OK.
  3. 5:  This step isolates the condition. Test the HO2S low reference circuit for an open or a high resistance, if the observed voltage is less than 100 mV.
DTC P0139 or P0159

Step Action Values Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 
IMPORTANT:
  • DTC P0139 is for bank 1 sensor 2 and DTC P0159 is for bank 2 sensor 2.
  • Ensure the HO2S is secure before proceeding with this DTC. A loose sensor could cause this DTC to set.
  1. Allow the engine to reach operating temperature.
  2. Operate the engine above 1,200 RPM for 2 minutes.
  3. Observe the appropriate HO2S 2 voltage parameter with a scan tool.
Is the voltage at the specified value?		 1,200 mV Go to Step 4  Go to Step 3 
3
  1. Observe the Freeze Frame and/or the Failure records data for this DTC.
  2. Turn the ignition OFF 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 and/or the Failure records data.
Did the DTC fail this ignition?		 - Go to Step 4  Go to Diagnostic Aids In This Test
4 
  1. Turn OFF the ignition.
  2. Disconnect the appropriate heated oxygen sensor (HO2S) 2.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a 3-amp fused jumper wire between the HO2S signal circuit and the low reference circuit.
  5. Observe the HO2S 2 voltage parameter with a scan tool.
Is the HO2S voltage less than specified value?		 100 mV Go to Step 8  Go to Step 5 
5 
  1. Connect the fused jumper wire between the HO2S signal circuit and a good ground.
  2. Observe the HO2S voltage parameter with a scan tool.
Is the voltage less than the specified value?		 100 mV Go to Step 7  Go to Step 6 
6 Test the signal circuit of the HO2S for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 9 
7 Test the low reference circuit of the HO2S for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 9 
8 Test for an intermittent and for a poor connection at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 10 
9 Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 11 
10 Replace the appropriate HO2S. Refer to the appropriate procedure:
Did you complete the replacement?		 - Go to Step 12  -
11
  1. Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
  2. Perform the idle learn procedure. Refer to Idle Learn .
Did you complete the replacement?		 - Go to Step 12  -
12
  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 13 
13 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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