Service Information

Captiva

DTC P0446

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 P0446: Evaporative Emissions (EVAP) Vent System Performance

This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. The engine control module (ECM) commands the EVAP purge solenoid valve Open and the EVAP canister vent solenoid valve Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the ECM commands the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Open. The ECM monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inch H2O in a calibrated time, this DTC sets.

Fuel Tank Pressure Sensor Signal Voltage	Fuel Tank Pressure
Less than 1.5 V	Positive Pressure
More than 1.5 V	Negative Pressure/Vacuum

Conditions for Running the DTC

•

DTCs P00C8, P00C9, P0068, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0122, P0123, P0125, P0128, P160E, P160D, P0191, P0192, P0193, P0222, P0223, P0443, P0449, P0452, P0453, P0454, P0502, P0503, P0606, P0722, P0723, P1106, P1107, P16F3, P1104, P2100, P2101, P2102, P2103, P2135, P2227, P2228, P2229, P2230 are not set.

•	The ignition voltage is between 11-32 V.

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

•	The fuel level is between 10-90 %.

•	The start-up engine coolant temperature (ECT) is less than 35°C (95°F).

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

•	The start-up ECT and IAT are within 9°C (48°F) of each other.

•	DTC P0446 runs once per trip when the above conditions have been met.

Conditions for Setting the DTC

The FTP sensor is more than -11 inches H2O vacuum for 2 s during the 13 minute test.

The FTP is less than -2.5 inches H2O or more than +5 inches H2O for 3 s after a cold start ignition ON.

Action Taken When the DTC Sets

DTC P0446 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0446 is a Type B DTC.

Diagnostic Aids

•	An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent solenoid valve inlet, or a pinched vent hose. A blockage in the vent system may also cause a poor fuel fill problem.

•	An EVAP canister filter that is restricted can cause this DTC to set. Refer to Evaporative Emission Canister Replacement .

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON and fuel cap removed, verify that the FTP sensor parameter is between 1.3-1.7 V.

⇒	If not within the specified range, go to the FTP sensor section in Circuit/System Testing.

Install the fuel cap.
With the engine running, the EVAP vent solenoid valve open, use a scan tool to command the EVAP purge solenoid valve to 100 %. The fuel tank vacuum should not increase to more than -15 mm Hg (-8 inches H2O).

⇒	If the fuel tank vacuum is greater than the specified range, go to the restriction section in Circuit/System Testing.

Using the scan tool, decrease the canister purge duty cycle from 100 % to 0 %. The vacuum should decrease to near zero.

⇒	If the fuel tank vacuum does not return to zero or appears to decrease too slowly go to the restriction section in Circuit/System Testing.

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 data.

Circuit/System Testing

Note: Perform the Circuit/System Verification before proceeding with the Circuit/System Testing.

Restriction

With the engine running, the EVAP vent solenoid valve open, and the EVAP purge solenoid valve commanded to 100 %, the fuel tank vacuum should not increase to more than -15 mm Hg (-8 inches H2O).

⇒	If the fuel tank vacuum is greater than the specified value, isolate the restriction by disconnecting one component at a time while the EVAP canister purge solenoid valve is commanded to 100 % and the vent valve is open.

Using the scan tool, decrease the canister purge duty cycle from 100 % to 0 %. The vacuum should decrease to near zero.

⇒	If the fuel tank vacuum does not return to zero, or appears to decrease too slowly, inspect the components in the EVAP vent system for a restriction.

Fuel Tank Pressure Sensor

Ignition OFF, disconnect the harness connector at the fuel tank pressure sensor.
Ignition OFF, test for less than 5 Ω between the low reference circuit terminal B and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the fuel tank pressure sensor.

Repair Instructions

•	Fuel Tank Pressure Sensor Replacement : LE5

•	Evaporative Emission Canister Vent Solenoid Valve Replacement

•	Evaporative Emission Canister Replacement

•	Control Module References for ECM replacement, setup and programming

Repair Verification

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

With the engine running, the EVAP canister vent solenoid valve open and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than -15 mm Hg (-8 inches H2O).