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HOMESERVICE MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 303 (ENGINE CONTROL SYSTEM - 3.6L (LY7) - DTC P0442 TO DTC P1551)DTC P0499TEST 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 Buick LaCrosse and 2006 Buick Allure. 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. 2:  This step determines if a condition exists. An audible click should be heard when the EVAP canister vent valve is commanded ON and OFF. Repeat the commands as necessary.
DTC P0499 Evaporative Emission (EVAP) Vent Solenoid Control Circuit High Voltage

Step Action Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module (ECM) 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 in Vehicle DTC Information
2 
  1. Turn ON the ignition, with the engine OFF.
  2. Command the evaporative emission (EVAP) canister vent valve ON and OFF with a scan tool.
Does the EVAP canister vent valve turn ON and OFF?		 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 EVAP canister vent valve harness connector. Refer to Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement .
  3. Turn ON the ignition, with the engine OFF
  4. Connect a test lamp between the control circuit of the EVAP canister vent valve to the engine control module (ECM) housing.
Does the test lamp illuminate?		 Go to Step 5  Go to Step 6 
5
IMPORTANT: The control circuit for the solenoid is pulled-up to voltage within the ECM, 2.6-4.6 volts on the control circuit is normal.
Test the control circuit of the EVAP canister vent valve 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 shorted terminals and for poor connections at the EVAP canister vent valve. 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 shorted terminals and for poor connections at the 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 10  Go to Step 9 
8 Replace the EVAP canister vent valve. Refer to Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement .
Did you complete the replacement?		 Go to Step 10  -
9 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 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 - Vehicle in Vehicle DTC Information 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.