DTC P0450 or P0451 (LAU or LBW)
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DTC P0450 or P0451 (LAU or LBW)
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DTC P0450
Fuel Tank Pressure Sensor Circuit
DTC P0451
Fuel Tank Pressure Sensor Performance
FTP Sensor
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Circuit
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Short to Ground
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Open
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Short to Voltage
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Operating Conditions:
Engine idling with closed loop control
Parameter Normal Range:
0.2-4.8 V
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5 V Reference Voltage
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0 V
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0 V
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5 V
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FTP Sensor Signal
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0 V
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0 V
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5 V
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Low Reference
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-
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4.2 V
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-
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Circuit/System Description
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The control module monitors the pressure in the fuel tank (FTP) via the sensor signal in order to detect vacuum decay and excess amounts of vacuum during the diagnostic test for the evaporative emission system (EVAP). The control module provides the sensor with a 5 V reference and a low reference to the FTP sensor. This DTC sets if the engine control module (ECM) detects one of the following conditions:
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The FTP sensor signal voltage is not within a calibrated range on a cold start-up.
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The FTP sensor signal oscillates greater than a calibrated amount when vehicle speed is within a predetermined range.
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The following table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.
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FTP Sensor Signal Voltage
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Fuel Tank Pressure
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High, Approximately 1.5 V or More
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Negative Pressure/Vacuum
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Low, Approximately 1.5 V or Less
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Positive Pressure
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Conditions for Running the DTC
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P0450
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DTC P0100, P0101, P0102, P0103, P0116, P0117, P0118, P0119, P0443, P0449, P0458, P0459, P0498, P0499, P0506, P0507, P050A, P0700, P2227, P2228, or P2229 is not set.
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The engine is operating.
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The ambient air temperature is greater than -7°C (+19°F).
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The vehicle speed is less than 30 km/h (19 mph).
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The ECM has commanded the EVAP canister vent valve open for greater than 4 s.
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DTC P0450 runs continuously when the above conditions are met for approximately 25 s.
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P0451 Condition 1
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DTC P0100, P0101, P0102, P0103, P0116, P0117, P0118, P0119, P0443, P0449, P0458, P0459, P0498, P0499, P050A, P0506, P0507, P0700, P2227, P2228, or P2229 is not set.
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The engine is operating for greater than 1 s.
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The engine is operating at idle.
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The ambient air temperature is warmer than -7°C (+19°F).
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The vehicle speed is less than 10 km/h (6 mph) for greater than 30 s.
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The BARO is greater than 68 kPa.
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The fuel level is between 11-88 %.
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The ECM has commanded the EVAP canister purge solenoid ON.
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The ECM has commanded the EVAP canister vent valve closed for greater than 4 s.
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DTC P0451 runs continuously when the above conditions are met for approximately 25 s.
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P0451 Condition 2
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DTC P0100, P0101, P0102, P0103, P0116, P0117, P0118, P0119, P0443, P0449, P0458, P0459, P0498, P0499, P050A, P0506, P0507, P0700, P2227, P2228, or P2229 is not set.
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The engine is operating.
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The BARO is greater than 68 kPa.
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The ECM has commanded the EVAP canister purge solenoid OFF.
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The ECM has commanded the EVAP canister vent valve open.
OR
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The vehicle speed is between 10-76 km/h (6-47 mph) for greater than 30 s.
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The fuel level is between 11-73 %.
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The EVAP purge solenoid is commanded ON.
OR
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The calculated ambient air temperature is 4-35°C (39-95°F) for greater than 3 s.
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DTC P0451 runs continuously when the above conditions are met for approximately 7 s.
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Conditions for Setting the DTC
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P0450
The ECM detects that the FTP sensor signal oscillates greater than 6.09 mm/Hg (3.26 in. H2O) for 4 s, or for a cumulative of 30 s.
P0451
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The ECM detects that the FTP is less than -26.2 mm/Hg (-14.1 in. H2O) or greater than 11.0 mm/Hg (5.9 in. H2O) for 4 s or for a cumulative of 30 s.
OR
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The ECM detects a change in the zero point of FTP sensor signal greater than +/-5.16 mm/Hg (2.76 in. H2O) from the zero point at start up for 4 s, or a cumulative of 30 s.
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Action Taken When the DTC Sets
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DTC P0450 is Type B DTC.
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DTC P0451 is Type B DTC.
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Conditions for Clearing the MIL/DTC
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DTC P0450 is Type B DTC.
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DTC P0451 is Type B DTC.
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A blocked or clogged EVAP canister vent solenoid valve, or inlet may set these DTCs.
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Fuel 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
Special Tools
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J 41413-200
Evaporative Emissions System Tester (EEST)
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GE-41415-50
Fuel Tank Cap Adapter
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1.
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Ignition OFF, remove the fuel fill cap. Connect the
GE-41415-50
Cap Adapter to the fuel tank filler neck. Connect the
J 41413-200
EEST to the
GE-41415-50
Cap Adapter.
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2.
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Ignition ON, seal the EVAP system using the scan tool Purge/Seal function.
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3.
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Pressurize the EVAP system with nitrogen to 9.33 mm/Hg (5 in/H2O). Compare the scan tool Fuel Tank Pressure Sensor parameter to the
J 41413-200
EEST pressure/vacuum gauge. Verify the scan tool FTP sensor parameter is within +/-0.9 mmHg (+/-0.5 in.H2O) of the pressure/vacuum gauge.
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4.
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If not within the specified range, replace the B150 FTP sensor.
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5.
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Command the Q13 EVAP vent solenoid valve OPEN with a scan tool. Verify the scan tool FTP sensor parameter is -0.9 to +0.9 mmHg (-0.5 to +0.5 in.H2O).
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6.
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If not within the specified range, replace the B150 FTP sensor.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
Fuel Pressure Sensor Replacement
