P0451
(P0451) FUEL TANK PRESSURE SENSOR PERFORMANCE
When Monitored and Set Condition
^ When Monitored: With the engine running at idle speed.
^ Set Condition: Low limit: The Fuel Tank Pressure Sensor voltage is less than 0.1 volt for 10 seconds. High limit: The Fuel Tank Pressure Sensor voltage is greater than 4.7 volts for 10 seconds. Signal curve: The Fuel Tank Pressure Sensor Performance code will be set if the signal remains constant.
POSSIBLE CAUSES
OPEN FUEL TANK PRESSURE SENSOR SIGNAL CIRCUIT
OPEN FUEL TANK PRESSURE SENSOR GROUND CIRCUIT
FUEL TANK PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
FUEL TANK PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
OPEN 5-VOLT SUPPLY
5-VOLT SUPPLY SHORTED TO VOLTAGE
5-VOLT SUPPLY SHORTED TO GROUND
FUEL TANK PRESSURE SENSOR
POWERTRAIN CONTROL MODULE
Diagnostic Test
1. READING FUEL TANK PRESSURE
Note: If an Evap System fault has been set, diagnose the Evap fault before continuing. Turn the ignition on. With the DRB III, monitor the Fuel Tank Press Diff.
Is the Fuel Tank Pressure above +30 hPa?
Yes>> Go To 2
No>> Go To 4
2. FUEL TANK PRESSURE SENSOR SIGNAL SHORTED TO VOLTAGE
Turn the ignition off. Disconnect the PCM C4 harness connector. Disconnect the Fuel Tank Pressure Sensor connector.
Note: Check connectors-Clean/repair as necessary. Turn the ignition on. Measure the voltage of the Fuel Tank Pressure Sensor Signal circuit at the Fuel Tank Pressure Sensor harness connector.
Is the voltage above 1.0 volt?
Yes>> Repair the Fuel Tank Pressure Sensor Signal for a short to voltage.
Perform Powertrain Verification Test - Ver 2
No>> Go To 3
3. OPEN FUEL TANK PRESSURE SENSOR GROUND CIRCUIT
Turn the ignition off. Measure the resistance of the Fuel Tank Pressure Sensor Ground circuit from the Fuel Tank Pressure Sensor harness connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
Yes>> Replace the Fuel Tank Pressure Sensor.
Perform Powertrain Verification Test - Ver 2
No>> Repair the Fuel Tank Pressure Sensor Ground circuit for an open.
Perform Powertrain Verification Test - Ver 2
4. FUEL TANK PRESSURE SENSOR
Turn the ignition off.
Disconnect the Fuel Tank Pressure Sensor harness connector.
Note: Check connectors-Clean/repair as necessary. Turn the ignition on. Connect a fused jumper between the Fuel Tank Pressure Sensor Signal circuit and the Fuel Tank Pressure Sensor 5-Volt Supply circuit.
Is the Fuel Tank Pressure above +30 hPa?
Yes>> Replace the Fuel Tank Pressure Sensor.
Perform Powertrain Verification Test - Ver 2
No>> Go To 5
5. FUEL TANK PRESSURE SENSOR 5-VOLT SUPPLY
With the ignition on.
Measure the voltage of the Fuel Tank Pressure Sensor 5-Volt Supply circuit at the Fuel Tank Pressure Sensor harness connector.
Is the voltage between 4.7 and 5.2 volts?
Yes>> Go To 8
No>> Go To 6
6. FUEL TANK PRESSURE SENSOR 5-VOLT SUPPLY SHORTED TO GROUND
Turn the ignition off.
Disconnect the PCM C4 harness connector.
Note: Check connectors-Clean/repair as necessary. Measure the resistance between ground and the Fuel Tank Pressure Sensor 5-Volt Supply circuit.
Is the resistance below 100 ohms?
Yes>> Repair the Fuel Tank Pressure Sensor 5-Volt Supply circuit for a short to ground.
Perform Powertrain Verification Test - Ver 2
No>> Go To 7
7. OPEN FUEL TANK PRESSURE SENSOR 5-VOLTS SUPPLY CIRCUIT
With the ignition off. Measure the resistance of the Fuel Tank Pressure Sensor 5-Volt Supply circuit from the PCM harness connector and the Fuel Tank Pressure Sensor harness connector.
Is the resistance below 5.0 ohms?
Yes>> Repair the Fuel Tank Pressure 5-Volt Supply circuit for an open.
Perform Powertrain Verification Test - Ver 2
No>> Replace and program the Powertrain Control Module.
Perform Powertrain Verification Test - Ver 2
8. OPEN FUEL TANK PRESSURE SENSOR SIGNAL
Turn the ignition off.
Disconnect the PCM C4 harness connector.
Note: Check connectors-Clean/repair as necessary. Measure the resistance of the Fuel Tank Pressure Sensor Signal circuit from the PCM harness connector and the Fuel Tank Pressure Sensor harness connector.
Is the resistance below 5.0 ohms?
Yes>> Repair the Fuel Tank Pressure Sensor Signal circuit for an open.
Perform Powertrain Verification Test - Ver 2
No>> Go To 9
9. FUEL TANK PRESSURE SENSOR SIGNAL SHORTED TO GROUND
With the ignition off.
Measure the resistance between ground and the Fuel Tank Pressure Sensor Signal circuit.
Is the resistance below 100 ohms?
Yes>> Repair the Fuel Tank Pressure Sensor Signal circuit for a short to ground.
Perform Powertrain Verification Test - Ver 2
No>> Replace and program the Powertrain Control Module.
Perform Powertrain Verification Test - Ver 2