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HOMESERVICE MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 383 (ENGINE CONTROL SYSTEM - 5.3L - DTC P0136 TO DTC P0446)DTC P0140TEST DESCRIPTION
2006 Chevrolet Cobalt SS, 4D Sedan, Standard

Test Description

2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Test Description
WARNING: This page is about a different car, the 2006 Chevrolet Monte Carlo and 2006 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 3:  If the voltage is varying above and below the specified value, the condition is not present.
DTC P0140

Step Action Value(s) Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Engine Control Module (ECM) Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Start the engine.
  2. Wait 1 minute to allow the heated oxygen sensor (HO2S) heater current to stabilize.
  3. Observe the affected HO2S heater current parameter with a scan tool.
Is the HO2S heater current parameter within the specified range?		 0.25-1.375 A Go to Step 3  Go to DTC P0135 or P0141
3 
  1. Allow the engine to reach operating temperature. Refer to Scan Tool Data List .
  2. Operate the engine at 1,500 RPM for 30 seconds.
  3. While observing the affected HO2S voltage parameter with a scan tool, quickly cycle the throttle from closed throttle to wide open throttle 3 times.
Did the HO2S voltage parameter change more than the specified value?		 200 mV Go to Step 4  Go to Step 5 
4
  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 5  Go to Testing for Intermittent Conditions and Poor Connections
5
  1. Turn OFF the ignition.
  2. Disconnect the affected HO2S.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the HO2S voltage parameter with a scan tool.
Is the HO2S voltage parameter more than the specified value?		 800 mV Go to Step 7  Go to Step 6 
6 Measure the voltage from the high signal circuit of the HO2S harness connector on the engine harness side to a good ground with a DMM. Refer to Circuit Testing .
Is the voltage more than the specified value?		 0.2 V Go to Step 8  Go to Step 9 
7
IMPORTANT: The sensor may be damaged if the circuit is shorted to a voltage source.
Test the HO2S high signal circuit for a short to voltage. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs .Did you find and correct the condition?		 - Go to Step 17  Go to Step 14 
8 Measure the voltage from the low signal circuit of the HO2S harness connector on the engine harness side to a good ground with a DMM. Refer to Circuit Testing .
Is the voltage more than the specified value?		 2 V Go to Step 12  Go to Step 10 
9 Test the HO2S high signal circuit for an open or high resistance. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 17  Go to Step 14 
10
  1. Connect a 3-amp fused jumper wire between the high signal circuit of the HO2S harness connector on the engine harness side and the low signal circuit of the HO2S harness connector on the engine harness side.
  2. Observe the HO2S voltage parameter with a scan tool.
Is the HO2S voltage parameter less than the specified value?		 100 mV Go to Step 13  Go to Step 11 
11 Test the HO2S low signal circuit for an open or high resistance. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 17  Go to Step 14 
12 Test the HO2S low signal circuit for a short to voltage. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 17  Go to Step 14 
13 Test for shorted terminals and for poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 17  Go to Step 15 
14 Test for shorted terminals and for poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor (HO2S) Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 17  Go to Step 16 
15 Replace the affected HO2S. Refer to Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 2 .
Did you complete the replacement?		 - Go to Step 17  -
16 Replace the ECM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 17  -
17
  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 18 
18 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
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.