P0451
DTC P0450 or P0451Diagnostic Instructions
^ Perform the [Diagnostic System Check - Vehicle Diagnostic Information] prior to using this diagnostic procedure. Diagnostic System Check - Vehicle Diagnostic Information
^ Review [Strategy Based Diagnosis] for an overview of the diagnostic approach. Strategy Based Diagnosis
^ [Diagnostic Procedure Instructions - Vehicle Diagnostic Information] provides an overview of each diagnostic category. Diagnostic Procedure Instructions - Vehicle Diagnostic Information
DTC Descriptors
DTC P0450 Fuel Tank Pressure (FTP) Sensor Circuit
DTC P0451 Fuel Tank Pressure (FTP) Sensor Performance
Typical Scan Tool Data
Circuit/System Description
The control module monitors the fuel tank pressure (FTP) 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 FTP sensor. This DTC sets if the engine control module (ECM) detects one of the following conditions:
^ The FTP sensor signal voltage is not within a calibrated range on a cold start-up.
^ The FTP sensor signal oscillates more than a calibrated amount when vehicle speed is less than 30 km/h (50 mph).
The following table illustrates the relationship between FTP 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 30 km/h (19 mph).
^ The ECM has commanded the EVAP canister vent valve open for greater than 3 seconds.
^ DTC P0450 runs continuously once the above conditions are met for approximately 25 seconds.
P0451
^ 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 25 seconds.
^ The engine is idling.
^ The ambient air temperature is greater than -7 °C (19 °F).
^ The vehicle speed is greater than 10 km/h (6 mph) for greater than 29 seconds.
^ The BARO is greater than 68 kPa.
^ The fuel level is between 12-88 percent.
^ The ECM has commanded the EVAP canister purge solenoid OFF.
^ The ECM has commanded the EVAP canister vent valve closed for greater than 4 seconds.
^ DTC P0451 runs continuously once the above conditions are met for approximately 25 seconds.
Or
^ 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 12-88 percent.
^ The ECM has commanded the EVAP canister purge solenoid OFF.
^ The ECM has commanded the EVAP canister vent valve open.
^ The vehicle speed is between 10-76 km/h (6-47 mph).
^ DTC P0451 runs continuously once the above conditions are met for approximately 7 seconds, 25 seconds for LLT.
Conditions for Setting the DTC
P0450
The ECM detects that the FTP sensor signal oscillates greater than 3.26 in. H2O (6.09 mm/Hg) for 4 seconds, or for a cumulative of 30 seconds.
P0451
^ The ECM detects that the FTP is less than -14.1 in. H2O (-26.2 mm/Hg) or greater than 5.7 in. H2O (10.6 mm/Hg) for 4 seconds or for a cumulative of 30 seconds.
Or
^ The ECM detects a change in the zero point of FTP sensor signal greater than +/- 2.73 in. H2O (5.10 mm/Hg) from the zero point at start up for 4 seconds, or a cumulative of 30 seconds.
Action Taken When the DTC Sets
^ DTC P0450 is Type B DTC.
^ DTC P0451 is Type B DTC.
Conditions for Clearing the MIL/DTC
^ DTC P0450 is Type B DTC.
^ DTC P0451 is Type B DTC.
Diagnostic Aids
^ A blocked or clogged EVAP canister vent may set this DTC.
^ A large leak in the EVAP system could cause this DTC to set.
Circuit/System Testing
1. Remove the fuel fill cap. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50.
2. Seal the system using the Purge Seal function with a scan tool.
3. Pressurize the EVAP system with nitrogen to 5 inches H2O. Compare the Fuel Tank Pressure Sensor parameter to the J 41413-200 pressure/vacuum gage. The FTP sensor should be within 1 inch H2O of the pressure/vacuum gage.
^ If the FTP is not within 1 inch H2O of the pressure/vacuum gage, replace the FTP sensor.
4. Command the vent solenoid valve OPEN with a scan tool.
^ If the FTP sensor parameter is not 0 inch H2O, replace the FTP sensor.
Repair Instructions
Perform the [Diagnostic Repair Verification - Vehicle Diagnostic Information] after completing the diagnostic procedure. Diagnostic Repair Verification - Vehicle Diagnostic Information
^ [Fuel Tank Pressure Sensor Replacement]