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DTC P0450 or P0451 (w/LAU or LBW)

DTC P0450 or P0451 (w/LAU or LBW)

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

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 V 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 V 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 within a predetermined range.


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 V or More

Negative Pressure/Vacuum

Low, Approximately 1.5 V 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, P0506, P0507, P050A, 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 4 s.

DTC P0450 runs continuously when the above conditions are met for approximately 25 s.



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 s.

The engine is operating at idle.

The ambient air temperature is warmer than -7°C (+19°F).

The vehicle speed is less than 10 km/h (6 mph) for greater than 30 s.

The BARO is greater than 68 kPa.

The fuel level is between 11-88 %.

The ECM has commanded the EVAP canister purge solenoid ON.

The ECM has commanded the EVAP canister vent valve closed for greater than 4 s.

DTC P0451 runs continuously when the above conditions are met for approximately 25 s.



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 ECM has commanded the EVAP canister purge solenoid OFF.

The ECM has commanded the EVAP canister vent valve open.

OR

The vehicle speed is between 10-76 km/h (6-47 mph) for greater than 30 s.

The fuel level is between 11-73 %.

The EVAP purge solenoid is commanded ON.

OR

The calculated ambient air temperature is 4-35°C (39-95°F) for greater than 3 s.

DTC P0451 runs continuously when the above conditions are met for approximately 7 s.


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 s, or for a cumulative of 30 s.


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 4 s or for a cumulative of 30 s.

OR

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.


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 solenoid valve, or inlet 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


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 41413-200 Evaporative Emissions System Tester (EEST)

GE-41415-50 Fuel Tank Cap Adapter

For equivalent regional tools, refer to Special Tools .


Circuit/System Testing


1. 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.

2. Ignition ON, seal the EVAP system using the scan tool Purge/Seal function.

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 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.

4. If not within the specified range, replace the B150 FTP sensor.

5. 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).

6. If not within the specified range, replace the B150 FTP sensor.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Pressure Sensor Replacement