DTC P0449, P0498, or P0499 (LAU or LBW)
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DTC P0449, P0498, or P0499 (LAU or LBW)
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DTC P0449
Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit
DTC P0498
Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit Low Voltage
DTC P0499
Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit High Voltage
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Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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Ignition Voltage
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P0499
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P0498
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EVAP Canister Vent Solenoid Valve Control Circuit
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P0498
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P0449
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P0499
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Circuit/System Description
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The evaporative emission (EVAP) canister vent valve is used for EVAP system diagnostics. The EVAP canister vent valve is a normally open valve. Battery positive voltage is supplied directly to the EVAP canister vent valve. The engine control module (ECM) controls the solenoid by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. If the ECM detects the control circuit voltage is within a predetermined range when the circuit is commanded OFF, this DTC sets.
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Conditions for Running the DTC
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The engine speed is more than 80 RPM.
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The ignition voltage is between 10-18 V.
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The ECM has commanded the EVAP canister vent valve ON and OFF at least once during the ignition cycle.
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The DTCs run continuously when the above conditions are met.
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Conditions for Setting the DTC
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P0449
The ECM detects the voltage on the EVAP canister vent valve control circuit is between 2.6-4.6 V when the driver is commanded OFF. The condition exists for less than 4 s or for a cumulative of 30 s.
P0498
The ECM detects the voltage on the EVAP canister vent valve control circuit is less than 2.6 V when the driver is commanded OFF. The condition is present for greater than 4 s or for a cumulative of 30 s.
P0499
The ECM detects the voltage on the EVAP canister vent valve control circuit is greater than 4.6 V when the driver is commanded ON. The condition is present for greater than 4 s or for a cumulative of 30 s.
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Action Taken When the DTC Sets
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DTC P0449, P0498 and P0499 are Type B DTCs.
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The EVAP system will only purge during Open Loop.
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Conditions for Clearing the DTC
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DTC P0449, P0498 and P0499 are Type B DTCs.
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Evaporative Emission Control System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References
for scan tool information
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Circuit/System Verification
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1.
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Command the EVAP vent solenoid valve ON and OFF with the scan tool. An audible click should be heard when changing between the commanded states.
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2.
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Start the engine, observe the scan tool EVAP Vent Solenoid Valve Circuit Test Status parameters. The circuit test status parameters should display OK or Not Run.
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3.
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With the engine idling, check the DTC Info with a scan tool. DTC P0449, P0498 or P0499 are not set.
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4.
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Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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1.
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Ignition OFF, disconnect the Q13 EVAP vent solenoid valve harness connector.
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2.
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Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal A and ground.
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3.
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If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.
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4.
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Ignition OFF, connect a test lamp between the control circuit terminal B and the ignition voltage circuit terminal A.
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5.
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Note
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The control circuit for the EVAP vent solenoid valve is pulled-up to voltage within the ECM, 2.6-4.6 volts on the control circuit is normal.
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Ignition ON, command the scan tool EVAP vent solenoid valve ON and OFF. The test lamp should turn ON and OFF.
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6.
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If the test lamp remains ON all the time, test the control circuit for a short to ground. If circuit/connections test normal, replace the K20 ECM.
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7.
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If the test lamp remains OFF all the time, test the control circuit for a short to voltage or an open/high resistance. If circuit/connections test normal, replace the K20 ECM.
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8.
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Test for 2.6-4.6 V between the control circuit terminal B and ground.
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9.
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If not within the specified range, replace the K20 ECM.
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10.
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If all circuits/connections test normal, test or replace the Q13 EVAP vent solenoid valve.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
