P0450
DTC P0450 or P0451 (LAU)
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 Descriptors
DTC P0450
Fuel Tank Pressure Sensor Circuit
DTC P0451
Fuel Tank Pressure Sensor Performance
Typical Scan Tool Data
Circuit/System Description
The control module monitors the fuel tank pressure sensor signal in order to detect vacuum decay and excess vacuum during the evaporative emission (EVAP) diagnostic test. The control module supplies a 5-volt reference and a low reference circuit to the fuel tank pressure sensor. This DTC sets if the engine control module (ECM) detects one of the following conditions:
- The fuel tank pressure sensor signal voltage is not within a calibrated range on a cold start-up.
- The fuel tank pressure sensor signal oscillates greater than a calibrated amount when vehicle speed is within a predetermined range.
The following table illustrates the relationship between fuel tank pressure sensor signal voltage and the EVAP system pressure/vacuum.
Conditions for Running the DTC
P0450
- 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.
- The engine is operating.
- The ambient air temperature is greater than -7 °C (+19 °F).
- The vehicle speed is less than 31 km/h (19 mph).
- The ECM has commanded the EVAP canister vent valve open for greater than 3 seconds, 4 seconds for LLT.
- DTC P0450 runs continuously once the above conditions are met for approximately 25 seconds.
P0451 Condition 1
- 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.
- The engine is operating for greater than 1 second.
- The engine is idling.
- The ambient air temperature is greater than -7 �C (+19 �F).
- The vehicle speed is less than 10 km/h (6 mph) for greater than 29 seconds.
- The BARO is greater than 68 kPa.
- The fuel level is between 11-88 percent.
- The ECM has commanded the EVAP canister purge solenoid ON.
- The ECM has commanded the EVAP canister vent valve closed for greater than 4 seconds.
- DTC P0451 runs continuously when the above conditions are met for approximately 25 seconds.
P0451 Condition 2
- 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.
- The engine is operating.
- The BARO is greater than 68 kPa.
- The fuel level is between 11-88 percent.
- The ECM has commanded the EVAP canister purge solenoid OFF.
- The ECM has commanded the EVAP canister vent valve open.
OR
- The fuel level is less than 60 percent, 73 percent for LLT.
- The vehicle speed is between 10-76 km/h (6-47 mph) for greater than 30 seconds.
- The ECM has commanded the EVAP canister purge solenoid ON.
OR
- The calculated ambient air temperature is between 4-35 °C (39-95 °F) for greater than 3 seconds.
- DTC P0451 runs continuously when the above conditions are met for approximately 7 seconds.
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
- 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
- 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.
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
Connector End View Reference
Component Connector End Views
Description and Operation
Evaporative Emission Control System Description Description and Operation
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
Special Tools
- J 41413-SPT High Intensity White Light
- J 41413-VLV EVAP Port Vent Fitting Tool
- J 41413-200 Evaporative Emissions System Tester (EEST)
- J 41413-300 EVAP Cap and Plug Kit
- CH-48096 EVAP Service Port Access Tool
- GE-41415-50 Fuel Tank Cap Adapter
Circuit/System Testing
1. 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.
2. Ignition ON, seal the system using the Purge Seal function with a scan tool.
3. 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 value on the pressure/vacuum gauge in J 41413-200. Check that the parameter for the pressure sensor in the fuel tank is within ±0.9 Hg (±0.5 inch H2O) on the pressure/vacuum gauge.
4. If not within the specified range, replace the B150 fuel tank pressure sensor.
5. 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).
6. If not within the specified range, replace the B150 fuel tank pressure sensor.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Fuel Tank Pressure Sensor Replacement