Diagnostic Instructions
DTC Descriptors
DTC P0450: Fuel Tank Pressure (FTP) Sensor Circuit
DTC P0451: Fuel Tank Pressure (FTP) Sensor Performance
Typical Scan Tool Data
FTP Sensor
Circuit
| Short to Ground
| Open
| Short to Voltage
|
Operating Conditions:
Engine operating in Closed Loop at idle
Parameter Normal Range:
0.2-4.8 V
|
5-Volt Reference Voltage
| 0 V
| 0 V
| 5 V
|
FTP Sensor Signal
| 0 V
| 0 V
| 5 V
|
Low Reference
| --
| 4.2 V
| --
|
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 greater than a calibrated amount when vehicle speed is less than 31 km/h (19 mph). |
The following table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.
FTP 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
| • | 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 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 26 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. |
| • | The fuel level is less than 60 percent, 73 percent for LLT. |
| • | The vehicle speed is between 10-76 km/h (6-47 mph) fro greater than 30 seconds. |
| • | The ECM has commanded the EVAP canister purge solenoid ON. |
| • | 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 FTP is less than -26.2 mm/Hg (-14.1 in. H2O) or greater than 11.0 mm/Hg (5.9 in. H2O) for 10 seconds or for a cumulative of 30 seconds. |
| • | 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 10 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
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
| • | J 41413-200
Evaporative Emissions System Tester (EEST) |
| • |
CH-48096
EVAP Service Port Access Tool |
Circuit/System Testing
- 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
.
- Seal the system using the Purge Seal function with a scan tool.
- 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
pressure/vacuum gage. Verify
the FTP sensor parameter is within +/-0.9 mmHg (+/-0.5 in.H2O) of the pressure/vacuum gage.
| ⇒ | If not within the specified range, replace the FTP sensor. |
- Command the 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).
| ⇒ | If not within the specified range, replace the FTP sensor. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
