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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1870 (Engine Controls And Fuel - 3.5L (L66) - DTC P2227 To DTC P2649) >> DTC P2252 or P2255 >> 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:  This step determines whether a condition currently exists. If the lambda value fluctuates near 1.00 and Loop Status is Closed, the HO2S is operating correctly.
  2. 4:  This step tests for a condition in the low reference circuit. Test for a short to ground, or a wire to wire short to the HO2S reference ground circuit, if the voltage measures less than 1 volt.
  3. 6:  Inspect the HO2S connector for water intrusion, corrosion, and bent or damaged terminals.
  4. 7:  Inspect the PCM connectors for water intrusion, corrosion, and bent or damaged terminals.
  5. 9:  After replacing the PCM, a new minimum throttle position and idle speed must be established.
DTC P2252 or P2255

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 P2252 is for bank 1 sensor 1 - rear and DTC P2255 is for bank 2 sensor 1 - front.
  1. Allow the engine to reach operating temperature.
  2. Observe the Loop Status Bank 1 or Loop Status Bank 2 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 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 Diagnostic Aids
4 
  1. Turn OFF the ignition.
  2. Disconnect the appropriate heated oxygen sensor (HO2S) connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the HO2S low reference circuit and a good ground with a DMM.
Is the voltage less than the specified value?		 1 V Go to Step 5  Go to Step 6 
5 Test the low reference circuit of the HO2S for a short to ground, or a short to the reference ground circuit of the HO2S. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 10  Go to Step 7 
6  Test for shorted terminals and for poor connections at the HO2S sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 10  Go to Step 8 
7  Test for shorted terminals and for poor connections at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 10  Go to Step 9 
8 Replace the HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .
Did you complete the replacement?		 - Go to Step 10  -
9 
  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 10  -
10
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 90 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 - Vehicle System OK
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