For 1990-2009 cars

### 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 Continuous Purge Flow

### 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

• | DTCs P0106, P0107, P0108, P0112, P0113, P0114, P0116, P0117, P0118, P0122, P0123, P0222, P0223, P0443, P0449, P0452, P0453, P0454, and P0502 are not set.

• | The ECM is not commanding reduced engine power.

• | The ignition is OFF for greater than 8 hours.

• | The ignition voltage is between 11-18 volts.

• | The barometric pressure (BARO) is greater than 70 kPa.

• | The start-up IAT is between 4-30°C (39-86°F).

• | The start-up ECT is less than 35°C (95).

• | The fuel level is between 10-90 percent.

• | The EVAP canister purge and EVAP vent valves are closed.

• | The DTC run once an ignition cycle when the above conditions are met.

### Conditions for Setting the DTC

The FTP sensor indicates vacuum during a non-purge condition.

### Action Taken When the DTC Sets

DTC P0496 is a Type B DTC.

### Conditions for Clearing the DTC

DTC P0496 is a Type B DTC.

### Diagnostic Aids

The EVAP system tests run when 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.

### Reference Information

#### Schematic Reference

Evaporative Emissions Hose Routing Diagram

#### 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 Verification

1. Engine idling, observe the Fuel Tank Pressure Sensor pressure parameter with a scan tool. The reading should display 0.00 inches of H2O.
2. 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.

### Circuit/System Testing

1. Ignition ON, engine OFF, observe the scan tool Fuel Tank Pressure Sensor pressure parameter. The reading should display 0.00 inches of H2O.

⇒ | If not the specified value, replace the FTP sensor.

Note: Additional DTCs will set when disconnecting components.

2. Ignition OFF, disconnect the harness connector at the EVAP canister purge solenoid.

Note: Depending on ambient air temperature, and fuel tank level, the fuel tank pressure may increase as the engine idles and the fuel warms up.

3. Engine idling, command the EVAP vent solenoid ON with a scan tool. Verify the Fuel Tank Pressure Sensor pressure parameter display equal to, or greater than 0.00 inches of H2O.

⇒ | If less than the specified value, replace the Evaporative Emission Canister Purge Solenoid Valve.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Fuel Tank Pressure Sensor Replacement

• | Evaporative Emission Canister Purge Solenoid Valve Replacement