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Home >> Chevrolet >> 2004 >> Optra Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 1.6L (L91) - DTC P0107 To DTC P0335 >> DTC P0135 >> Test Description
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Test Description

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

  1. 1:  The Diagnostic System Check - Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool, if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
  2. 2:  This step determines if DTC P0135 is the result of a hard failure or an intermittent condition. With the ignition ON and the engine OFF, the front heated oxygen sensor (HO2S1) voltage displayed on the scan tool should change within several minutes toward 0 or 1 volt, indicating that the heater is working properly.
  3. 3:  Probing terminal 2 of the HO2S1 connector verifies if voltage is available to the HO2S1 heater.
  4. 4:  If voltage is available at the connector, then it becomes a good voltage source to inspect for a ground at terminal 3.
  5. 5:  This step determines if voltage is not available at the HO2S1 due to an open in the HO2S1 fuse or an open ignition feed circuit. If the fuse is open, determine if it was due to a short in the ignition feed circuit before replacing the fuse.
Step Action Values Yes No
1  Perform the Diagnostic System Check - Engine Controls.
Is the check complete?		 - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 
    IMPORTANT: If the engine has just been operating, allow the engine to cool for about one-half hour before proceeding.
  1. Turn ON the ignition, with the engine OFF.
  2. Install a scan tool.
Does the front heated oxygen sensor (HO2S1) voltage gradually change toward the specified voltage?		 0 V or 1 V Go to Step 13  Go to Step 3 
3 
  1. Disconnect the HO2S1 electrical connector.
  2. With a test light connected to ground, probe the ignition feed circuit, terminal 2 of the connector.
Does the test light illuminate?		 - Go to Step 4  Go to Step 5 
4  Connect a test light between the ignition feed and ground circuits, terminal 2 and 3 of the connector.
Does the test light illuminate?		 - Go to Step 6  Go to Step 7 
5  Inspect the fuse in the engine fuse block.
Is the fuse open?		 - Go to Step 8  Go to Step 9 
6 Inspect the connections terminal 2 and 1 at the HO2S1 connector and repair as necessary.
Is a repair necessary?		 - Go to Step 13  Go to Step 10 
7 Inspect the connections terminal 4 at the HO2S1 connector and repair as necessary.
Is a repair necessary?		 - Go to Step 13  Go to Step 11 
8
  1. Inspect for a short to ground in the HO2S1 ignition feed circuit and repair as necessary.
  2. Replace the open fuse.
Is the action complete?		 - Go to Step 13  -
9 Inspect the connections terminal 2 at the HO2S1 connector and repair as necessary.
Is the repair complete?		 - Go to Step 13  Go to Step 12 
10 Replace the HO2S1. Refer to Heated Oxygen Sensor Replacement - Sensor 1 .
Is the replacement complete?		 - Go to Step 13  -
11 Repair the open in the ignition feed circuit.
Is the action complete?		 - Go to Step 13  -
12 Repair the open in the ignition feed circuit.
Is the action complete?		 - Go to Step 13  -
13
  1. Use a scan tool in order to clear the DTCs.
  2. Start the engine and idle at normal operating temperature.
  3. Operate the vehicle within the Conditions for Setting the DTC as specified in the supporting text.
Does the scan tool indicate that this diagnostic has run and passed?		 - Go to Step 14  Go to Step 2 
14 Check if any additional DTCs are set.
Are any DTCs displayed that have not been diagnosed?		 - Go to DTC List System OK
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