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Home >> Buick >> 2007 >> Allure CXS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 3.6L - DTC P0135 To P0420 >> DTC P0135 >> Test Description
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Test Description

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

  1. 2:  This step determines if the condition exists. If there is an HO2S circuit condition, the ECM commands open loop for the applicable sensor.
  2. 4:  This step tests for a bias voltage across the reference voltage circuit and the low reference circuit of the HO2S. The bias voltage that you are measuring, is the voltage difference between the reference voltage circuit and the low reference circuit. If there is a condition with the reference voltage circuit or the low reference circuit of the HO2S, the bias voltage will be more than or less than the specified value.
  3. 5:  This step tests the ignition 1 voltage circuit of the HO2S for high resistance. If the voltage at the test lamp probe is not B+, there is a high resistance condition with the circuit.
  4. 10:  This step inspects the harness connector for water intrusion, corrosion, and bent or damaged pins.
  5. 11:  This step inspects the harness connector for water intrusion, corrosion, and bent or damaged pins.
DTC P0135

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine 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 
  1. Allow the engine to reach operating temperature.
  2. Observe the Loop Status for sensor 1 with a scan tool.
Does the scan tool display Closed Loop?		 - Go to Step 3  Go to Step 4 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 5 minutes.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text or as close to the Freeze Frame/Failure Records that you observed.
Does the DTC fail this ignition?		 - Go to Step 4  Go to Intermittent Conditions
4 
  1. Turn OFF the ignition.
  2. Disconnect the heated oxygen sensor (HO2S).
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the reference voltage circuit and the low reference circuit of the HO2S with a DMM.
Is the voltage within the specified range?		 350-550 mV Go to Step 5  Go to Step 7 
5 
    IMPORTANT: Use the J 35616-200  Test Lamp Kit for this test. See Special Tools . If the J 35616-200  is not available, use a test lamp that measures more than 20 ohms. See Special Tools .
  1. Connect a test lamp between the ignition 1 voltage circuit of the HO2S and a good ground.
  2. Measure the voltage between the probe of the test lamp and a good ground with a DMM. Refer to Measuring Voltage Drop .
Is the voltage at the specified value?		 B+ Go to Step 6  Go to Step 12 
6 Test the following circuits of the HO2S for high resistance:
  • The Heater control circuit
  • The reference voltage circuit
  • The low reference circuit

Refer to Circuit Testing .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
7 Measure the voltage between the reference voltage circuit of the HO2S and a good ground. Refer to Circuit Testing .
Is the voltage less than the specified value?		 3.5 V Go to Step 8  Go to Step 9 
8 Test the low reference circuit of the HO2S for the following:
  • An open
  • A short to the reference voltage circuit
  • High resistance

Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
9 Test the reference voltage circuit of the HO2S for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 11 
10  Test for shorted terminals and poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 13 
11  Test for shorted terminals and poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 14 
12 Repair the high resistance in the ignition 1 voltage circuit of the HO2S. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 15  -
13 Replace the HO2S. Refer to Heated Oxygen Sensor 1 Replacement .
Did you complete the replacement?		 - Go to Step 15  -
14 Replace the ECM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 15  -
15
  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 16 
16 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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