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Home >> Buick >> 2004 >> Century Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls (DTC P0140 To P0496) >> Engine Controls Diagnosis >> DTC P0496 >> Diagnostic Aids
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Diagnostic Aids

The EVAP system tests run when the engine is first started and meets the Conditions for Running the DTC. An intermittent condition could be caused by an improperly installed or damaged EVAP canister purge solenoid valve, or by a temporary blockage in the EVAP canister purge solenoid valve.

For intermittent conditions refer to Intermittent Conditions .

DTC P0496

Step Action Values Yes No
Schematic Reference:  Evaporative Emissions (EVAP) Hose Routing Diagram 
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. Observe the Freeze Frame/Failure Records for this DTC.
  2. Perform the Service Bay Test. Refer to Service Bay Test .
Does the scan tool indicate that the Service Bay Test passed?		 - Go to Diagnostic Aids Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Disconnect the purge line from the EVAP purge solenoid valve. Refer to Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement .
  3. Turn ON the ignition, with the engine OFF.
Is the Fuel Tank Pressure (FTP) sensor parameter within the specified range?		 -1 to +1 in H2O Go toStep 4  Go to Step 5 
4
  1. Install a hand held vacuum gage to the EVAP purge port.
  2. Disconnect the EVAP canister purge valve harness connector.
  3. Monitor vacuum on the vacuum gage.
  4. Start the engine and allow the engine to idle.
  5. Increase the idle to 1,200-1,500 RPM.
Does the vacuum gage indicate an increase in vacuum?		 - Go to Step 7  Go to Diagnostic Aids
5 Test for an intermittent and for a poor connection at the FTP sensor. 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 8  Go to Step 6 
6 Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement .
Did you complete the replacement?		 - Go to Step 8   
7 Replace the EVAP canister purge solenoid valve. Refer to Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement .
Did you complete the replacement?		 - Go toStep 8  -
8 Perform the Service Bay Test. Refer to Service Bay Test .
Does the scan tool indicate that the Service Bay Test passed?		 - Go to Step 9  Go to Step 3 
9 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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