DTC P0450 or P0451 (LAU)
| DTC P0450 or P0451 (LAU) |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| DTC Descriptors |
DTC P0450
Fuel Tank Pressure Sensor Circuit
DTC P0451
Fuel Tank Pressure Sensor Performance
| Typical Scan Tool Data |
Fuel Tank Pressure Sensor
| Circuit | Short to Ground | Open | Short to Voltage |
| Operating Conditions: Engine idling with closed loop control Parameter Normal Range: 0.2-4.8 V | |||
| 5-Volt Reference Voltage | 0 V | 0 V | 5 V |
| Fuel Tank Pressure Sensor Signal | 0 V | 0 V | 5 V |
| Low Reference | - | 4.2 V | - |
| Circuit/System Description |
The control module monitors the pressure in the fuel tank 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 fuel tank pressure sensor. This DTC sets if the engine control module (ECM) detects one of the following conditions:
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The fuel tank pressure sensor signal voltage is not within a calibrated range on a cold start-up.
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The fuel tank pressure 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 fuel tank pressure sensor signal voltage and the EVAP system pressure/vacuum.
| Fuel Tank Pressure 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 |
P0450
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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 ambient air temperature is greater than -7°C (+19°F).
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The vehicle speed is less than 31 km/h (19 mph).
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The ECM has commanded the EVAP canister vent valve open for greater than 3 seconds, 4 seconds for LLT.
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DTC P0450 runs continuously once the above conditions are met for approximately 25 seconds.
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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 second.
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The engine is idling.
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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 10 km/h (6 mph) for greater than 29 seconds.
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The BARO is greater than 68 kPa.
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The fuel level is between 11-88 percent.
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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 seconds.
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DTC P0451 runs continuously when the above conditions are met for approximately 25 seconds.
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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 fuel level is between 11-88 percent.
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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.
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The fuel level is less than 60 percent, 73 percent for LLT.
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The vehicle speed is between 10-76 km/h (6-47 mph) for greater than 30 seconds.
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The ECM has commanded the EVAP canister purge solenoid ON.
OR |
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The calculated ambient air temperature is between 4-35°C (39-95°F) for greater than 3 seconds.
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DTC P0451 runs continuously when the above conditions are met for approximately 7 seconds.
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| Conditions for Setting the DTC |
P0450
The ECM detects that the FTP sensor signal oscillates greater than 6.09 mm/Hg (3.26 in. H2O) for 4 seconds, or for a cumulative of 30 seconds.P0451
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The ECM detects that the fuel tank pressure is less than -26.2 mm/Hg (-14.1 in. H2O) or greater than 11.0 mm/Hg (5.9 in. H2O) for 4 seconds or for a cumulative of 30 seconds.
OR |
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The ECM detects a change in the zero point of fuel tank pressure sensor signal greater than +/-5.16 mm/Hg (2.76 in. H2O) from the zero point at start up for 4 seconds, or a cumulative of 30 seconds.
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| Action Taken When the DTC Sets |
DTCs P0450 and P0451 are Type B DTCs.
| Conditions for Clearing the MIL/DTC |
DTCs P0450 and P0451 are Type B DTCs.
| Diagnostic Aids |
A blocked or clogged EVAP canister vent may set these DTCs.
| Reference Information |
Schematic Reference
Engine Controls Schematics (3.0L (LF1)) Engine Controls Schematics (2.8L (LAU))
Connector End View Reference
Component Connector End Views
Description and Operation
Evaporative Emission Control System Description
Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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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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GE-41413 High Intensity White Light
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J 41413-VLV EVAP Port Vent Fitting Tool
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J 41413-200 Evaporative Emissions System Tester (EEST)
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J 41413-300 EVAP Cap and Plug Kit
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CH-48096 EVAP Service Port Access Tool
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GE-41415-50 Fuel Tank Cap Adapter
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| Circuit/System Testing |
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Ignition OFF, remove the fuel fill cap. Connect the GE-41415-50 to the fuel tank filler neck. Connect J 41413-200 to GE-41415-50.
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Ignition ON, seal the system using the Purge Seal function with a scan tool.
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Pressurise 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 fuel tank pressure sensor parameter is within +/-0.9 mmHg (+/-0.5 in. H2O) of the pressure/vacuum gauge.
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If not within the specified range, replace the B150 fuel tank pressure sensor.
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Command the EVAP vent solenoid valve OPEN with a scan tool. Verify the scan tool Fuel Tank Pressure Sensor parameter is -0.9 to +0.9 mmHg (-0.5 to +0.5 in.H2O).
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If not within the specified range, replace the B150 fuel tank pressure sensor.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Fuel Tank Pressure Sensor Replacement
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