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Home >> Buick >> 2004 >> Century Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls (DTC P0030 To P0138) >> Engine Controls Diagnosis >> DTC P0030 >> Test Description
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Test Description

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

  1. 4:  A DTC fail in this step verifies the condition is present with the HO2S 1 disconnected.
DTC P0030

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Controls Connector End Views  or  Powertrain Control Module (PCM) Connector End Views 
1 Did you perform the Diagnostic System Check-Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2
  1. Start the engine.
  2. Allow the engine to idle at operating temperature. Refer to Scan Tool Data List .
  3. Observe the heated oxygen sensor (HO2S) 1 Heater Current parameter with a scan tool.
  4. Allow the HO2S 1 Heater Current parameter to stabilize.
Is the amperage within the specified range?		 0.25-0.85 A 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 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 HO2S 1 connector.
  3. Start the engine.
  4. Allow the engine to idle at operating temperature.
  5. Observe the DTC Info parameter with a scan tool for at least 30 seconds.
Did the DTC fail this ignition?		 - Go to Step 5  Go to Step 6 
5 Test the HO2S 1 heater low control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 7 
6 Test for an intermittent and for a poor connection at the harness connector of the HO2S 1. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 8 
7 Test for an intermittent and for a poor connection at the harness connector of the powertrain control module (PCM). Refer toTesting for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 9 
8 Replace the HO2S 1. Refer to Heated Oxygen Sensor Replacement - Position 1 .
Did you complete the replacement?		 - Go to Step 10  -
9 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 - Go to Step 10  -
10
  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 11 
11 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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