2. Using the scan tool, decrease the canister purge duty cycle from 100 percent to 0 percent. The vacuum should decrease to near zero.
锟斤拷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
1. Ignition OFF, disconnect the harness connector at the B150 fuel tank pressure sensor.
2. Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 ohms between the low reference circuit terminal and
ground.
锟斤拷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
* Evaporative Emission System Hose/Pipe Replacement (2500 LWB - Intermediate) (See: Powertrain Management/Emission Control
Systems/Evaporative Emissions System/Evaporative Emissions Hose/Service and Repair/Evaporative Emission System Hose/Pipe
Replacement (2500 LWB - Intermediate))Evaporative Emission System Hose/Pipe Replacement (2500 LWB - 98.4L (26 gal) Tank-Front) (
See: Powertrain Management/Emission Control Systems/Evaporative Emissions System/Evaporative Emissions Hose/Service and
Repair/Evaporative Emission System Hose/Pipe Replacement (2500 LWB - 98.4L (26 gal) Tank-Front))
* Evaporative Emission Canister Vent Solenoid Valve Replacement (1500 Series) (See: Powertrain Management/Emission Control
Systems/Evaporative Emissions System/Evaporative Emission Control Canister/Canister Vent Valve/Service and Repair/Evaporative
Emission Canister Vent Solenoid Valve Replacement (1500 Series))Evaporative Emission Canister Vent Solenoid Valve Replacement (2500
Series) (See: Powertrain Management/Emission Control Systems/Evaporative Emissions System/Evaporative Emission Control
Canister/Canister Vent Valve/Service and Repair/Evaporative Emission Canister Vent Solenoid Valve Replacement (2500 Series))
* Evaporative Emission Canister Replacement (1500 Series) (See: Powertrain Management/Emission Control Systems/Evaporative Emissions
System/Evaporative Emission Control Canister/Service and Repair/Evaporative Emission Canister Replacement (1500 Series))Evaporative
Emission Canister Replacement (2500 Series) (See: Powertrain Management/Emission Control Systems/Evaporative Emissions
System/Evaporative Emission Control Canister/Service and Repair/Evaporative Emission Canister Replacement (2500 Series))
* Evaporative Emission Line Replacement - Engine (See: Powertrain Management/Emission Control Systems/Evaporative Emissions
System/Evaporative Emissions Hose/Service and Repair)
* Evaporative Emission Line Replacement - Chassis (2500 Series) (See: Powertrain Management/Emission Control Systems/Evaporative
Emissions System/Evaporative Emissions Hose/Service and Repair/Evaporative Emission Line Replacement - Chassis (2500 Series)
)Evaporative Emission Line Replacement - Chassis (1500 Series) (See: Powertrain Management/Emission Control Systems/Evaporative
Emissions System/Evaporative Emissions Hose/Service and Repair/Evaporative Emission Line Replacement - Chassis (1500 Series))
* Evaporative Emission System Cleaning (See: Powertrain Management/Emission Control Systems/Evaporative Emissions System/Service
and Repair)
* Fuel Tank Pressure Sensor Replacement (1500 LWB - 117.3L (31 gal) Tank + E85) (See: Powertrain Management/Computers and Control
Systems/Fuel Tank Pressure Sensor/Service and Repair/Fuel Tank Pressure Sensor Replacement (1500 LWB - 117.3L (31 Gal) Tank + E85)
)Fuel Tank Pressure Sensor Replacement (2500 Series) (See: Powertrain Management/Computers and Control Systems/Fuel Tank Pressure
Sensor/Service and Repair/Fuel Tank Pressure Sensor Replacement (2500 Series))Fuel Tank Pressure Sensor Replacement (1500 Series) (
See: Powertrain Management/Computers and Control Systems/Fuel Tank Pressure Sensor/Service and Repair/Fuel Tank Pressure Sensor
Replacement (1500 Series))Fuel Tank Pressure Sensor Replacement (1500 SWB - 98.4L (26 gal) Tank + E85) (See: Powertrain
Management/Computers and Control Systems/Fuel Tank Pressure Sensor/Service and Repair/Fuel Tank Pressure Sensor Replacement (1500
SWB - 98.4L (26 Gal) Tank + E85))
* Control Module References (See: Testing and Inspection/Programming and Relearning)
Repair Verification
Perform the Diagnostic Repair Verification (See: Verification Tests) 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 mmHg (-8 inches H2O).
P0449
DTC P0443 or P0449
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
