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DTC P0496

DTC P0496

Diagnostic Instructions


• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• Diagnostic Procedure Instructions provides an overview of each diagnostic category.


DTC Descriptor

DTC P0496

Evaporative Emissions (EVAP) System Flow During Non-Purge

Circuit Description

This DTC tests for continuous intake manifold vacuum flow to the Evaporative Emission (EVAP) System. The control module seals the EVAP system by commanding the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Closed. The control module monitors the fuel tank pressure (FTP) sensor to determine if a vacuum is being drawn on the EVAP system. If vacuum in the EVAP system is greater than a predetermined value within a predetermined time, this DTC sets.


FTP Sensor Signal Voltage Fuel Tank Pressure
High, Approximately 1.5 Volts or More

Negative Pressure/Vacuum

Low, Approximately 1.5 Volts or Less

Positive Pressure



Conditions for Running the DTC


• Before the engine control module (ECM) can report DTC P0496 failed, DTCs P0450, P0451, P0452, and P0453 must run and pass.

• DTC P0100, P0101, P0102, P0103, P0111, P0112, P0113, P0116, P0117, P0118, P0119, P0443, P0446, P0449, P0450, P0451, P0452, P0453, P0458, P0459, P0498, P0499, P0560, P0562, P0563, P0700, P2122, P2123, P2127, P2128, P2138, P2227, P2228, or P2229 is not set.

• The fuel system is in Closed Loop.

• The engine run time is greater than 10 min, or the long term fuel trim is stable.

• The vehicle speed sensor (VSS) is less than 3 km/h (2 mph).

• The engine is operating at idle.

• The ignition voltage is between 10-18 V.

• The Closed Loop fuel control is enabled.

• The fuel tank pressure (FTP) is between -10.0 and +5.0 in. H2O (-18.7 and +9.8 mm Hg).

• The ambient air temperature is between 2-32°C (36-90°F).

• The engine coolant temperature (ECT) is within 10°C (18°F) of the ambient air temperature at engine start.

• The fuel tank level is between 11-88 %.

• The barometric pressure (BARO) is greater than 68 kPa.

• The above conditions are met for greater than 30 s.

• DTC P0496 will attempt to run up to 10 times or the test completes successfully once per ignition cycle.


Conditions for Setting the DTC


• The control module detects vacuum during a non-purge condition.

• The condition is present for greater than 4 s or for a cumulative of 30 s.


Action Taken When the DTC Sets

DTC P0496 is a Type A/B DTC.

Conditions for Clearing the DTC

DTC P0496 is a Type A/B DTC.

Diagnostic Aids


• Observe the Freeze Frame/Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition occurs that caused the DTC to set. This may assist in diagnosing the condition.

• The EVAP system's tests are run when the engine is started and the conditions for running diagnostic trouble codes are met. A periodic condition can be caused by an incorrectly installed or damaged vent valve on the EVAP system's carbon filter holder, or by an intermittent stoppage or obstruction in the carbon filter holder's vent valve.


Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Evaporative Emission Control System Description

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing


1. Disconnect the Q12 EVAP purge solenoid valve electrical harness connector.

2. Start the engine.

3. Command the Q13 EVAP vent solenoid valve Closed with a scan tool.

4. Increase the engine speed to 1,200-1,500 RPM.

5. Observe the scan tool fuel tank pressure (FTP) sensor parameter. Verify the scan tool FTP sensor parameter is -0.9 to +0.9 mmHg (-0.5 to +0.5 in.H2O).

6. If not within the specified range, replace the Q12 EVAP purge solenoid valve.

7. Ignition ON, engine OFF, disconnect the EVAP purge hose/pipe at the Q12 EVAP purge solenoid valve.

8. Observe the scan tool FTP sensor parameter. Verify the FTP sensor parameter is -0.9 to +0.9 mm Hg (-0.5 to +0.5 in. H2O).

9. If not within the specified range, replace the B150 FTP sensor.


Repair Instructions


• Evaporative Emission Canister Purge Solenoid Valve Replacement

• Fuel Pressure Sensor Replacement

• Control Module References for Engine Control Module replacement, setup, and programming


Repair Verification


1. Start the engine.

2. Command the Q13 EVAP vent solenoid valve Closed with a scan tool.

3. Increase the engine idle to 1,200-1,500 RPM.

4. Observe the scan tool FTP sensor parameter. Verify the FTP sensor parameter is -0.9 to +0.9 mm Hg (-0.5 to +0.5 in. H2O).

5. Clear the DTCs with a scan tool.