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Home >> Cadillac >> 2006 >> STS Base, 3.6 7, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 16 (Engine Control System - 4.6L (LH2) - DTC P2138 To P2636) >> DTC P2231 or P2234 >> Conditions for Clearing the MIL/DTC

Conditions for Clearing the MIL/DTC

WARNING: This page is about a different variant/trim than selected.
DTC P2231 or P2234

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
IMPORTANT: During idle or steady throttle conditions, the lambda value will be very close to 1.000.
  1. Start the engine.
  2. Allow the engine to reach operating temperature. Refer to Scan Tool Data List .
  3. Operate the engine at 2,000 RPM for 1 minute.
  4. Observe the HO2S Bank 1 Sensor 1 or HO2S Bank 2 Sensor 1 parameter with a scan tool.
Is the lambda value varying within the specified range?		 0.900-1.100 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. Disconnect the connector for the heated oxygen sensor (HO2S) 1 that applies to this DTC.
  2. Visually and physically inspect for the following items:
    • The HO2S 1 is securely installed
    • Terminal corrosion or water intrusion
    • Terminal tension at the HO2S 1 connectors
    • Damaged wiring
  3. Repair as necessary. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 23  Go to Step 5 
5 Measure the voltage from the HO2S output pump current circuit, on the engine harness side connector, to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the voltage less than the specified value?		 100 mV Go to Step 6  Go to Step 11 
6 Measure the voltage from the HO2S heater low control circuit, on the engine harness side connector, to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the voltage less than the specified value?		 100 mV Go to Step 12  Go to Step 7 
7 Is the voltage within the specified range? 100-200 mV Go to Step 13  Go to Step 8 
8 Is the voltage within the specified range? 2.4-3 V Go to Step 14  Go to Step 9 
9 Measure the voltage from the HO2S reference voltage circuit, on the engine harness side connector, to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
Is the voltage within the specified range?		 2.8-3.1 V Go to Step 19  Go to Step 10 
10 Is the voltage more than the specified value? 2.8 V Go to Step 15  Go to Step 16 
11 Is the voltage within the specified range? 1-1.5 V Go to Step 17  Go to Step 18 
12
IMPORTANT:
  • The normal open circuit voltage of the output pump current circuit is approximately 10-65 millivolts.
  • The normal open circuit voltage of the heater low control circuit is 4.3-4.6 volts.
Test the HO2S output pump current circuit for a short to the HO2S heater low control circuit. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 23  Go to Step 20 
13
IMPORTANT:
  • The normal open circuit voltage of the input pump current circuit is approximately 10-65 millivolts.
  • The normal open circuit voltage of the heater low control circuit is 4.3-4.6 volts.
Test the HO2S input pump current circuit for a short to the HO2S heater low control circuit. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 23  Go to Step 20 
14
IMPORTANT:
  • The normal open circuit voltage of the low reference circuit is 2.4-2.7 volts.
  • The normal open circuit voltage of the heater low control circuit is 4.3-4.6 volts.
Test the HO2S low reference circuit for a short to the HO2S heater low control circuit. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 23  Go to Step 20 
15
IMPORTANT:
  • The normal open circuit voltage of the reference voltage circuit is 2.8-3.1 volts.
  • The normal open circuit voltage of the heater low control circuit is 4.3-4.6 volts.
Test the HO2S reference voltage circuit for a short to the HO2S heater low control circuit. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 23  Go to Step 20 
16 Test the HO2S reference voltage circuit for an open or high resistance. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 23  Go to Step 20 
17
IMPORTANT:
  • The normal open circuit voltage of the input pump current circuit is approximately 10-65 millivolts.
  • The normal open circuit voltage of the low reference circuit is 2.4-2.7 volts.
Test the HO2S input pump current circuit for a short to the HO2S low reference circuit. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 23  Go to Step 20 
18
IMPORTANT:
  • The normal open circuit voltage of the output pump current circuit is approximately 10-65 millivolts.
  • The normal open circuit voltage of the low reference circuit is 2.4-2.7 volts.
Test the HO2S output pump current circuit for a short to the HO2S low reference circuit. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.Did find and correct the condition?		 - Go to Step 23  Go to Step 20 
19 Test for poor connections and shorted terminals at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 23  Go to Step 21 
20 Test for poor connections and shorted terminals at the engine control module (ECM). 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 23  Go to Step 22 
21 Replace the affected HO2S. 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 23  -
22 Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 23  -
23
  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 24 
24 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 in Vehicle DTC Information System OK
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