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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 P0138 or P0158 >> 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 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. 2:  This step verifies that a condition exists.
  3. 4:  This step tests the signal circuit of the HO2S 2. Test the signal circuit for a short to voltage, if the voltage on the signal circuit is more than the specified value.
  4. 5:  This step isolates the condition. If the voltage on the signal circuit is more than the specified value after the PCM is disconnected, test the signal circuit for a wire to wire short to a voltage.
  5. 6:  This step isolates the condition. If the test lamp illuminates when the HO2S 2 heater is commanded ON, test the signal circuit for a short to the heater control circuit.
DTC P0138 or P0158

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 P0138 is for bank 1 sensor 2 and DTC P0158 is for bank 2 sensor 2.
  1. Allow the engine to reach operating temperature.
  2. Operate the engine speed above 1,200 RPM for 2 minutes.
  3. Observe the appropriate HO2S 2 voltage parameter with a scan tool.
Is the voltage more than the specified value?		 1,200 mV 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. 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 4  Go to Intermittent Conditions
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. Measure the voltage between the signal circuit of the HO2S 2 and a good ground with a DMM.
Is the voltage more than the specified value?		 750 mV Go to Step 5  Go to Step 6 
5 
  1. Turn OFF the ignition.
  2. Disconnect the powertrain control module (PCM).
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the signal circuit of the HO2S 2 and a good ground with a DMM.
Is the voltage less than the specified value?		 750 mV Go to Step 9  Go to Step 10 
6 
  1. Connect a test lamp between the signal circuit of the HO2S 2 and B+.
  2. Command the appropriate HO2S 2 Heater Control ON with a scan tool.
Does the test lamp illuminate?		 - Go to Step 7  Go to Step 8 
7 Test the signal circuit of the HO2S 2 for a short to the heater control circuit of the HO2S 2. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 9 
8 Test for shorted terminals and for poor connections 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 13  Go to Step 11 
9 Test shorted terminals and for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 13  Go to Step 12 
10 Repair the short to voltage in the signal circuit of the HO2S 2. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 13  -
11 Replace the appropriate HO2S. Refer to the appropriate procedure:
Did you complete the replacement?		 - Go to Step 13  -
12
  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 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. 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 14 
14 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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