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DTC P0451: Evaporative Emission Control System Pressure Sensor Range/Performance
 
 
 
 
CIRCUIT OPERATION
  • The ECM terminal FPR5 supplies a 5 volts reference signal to the fuel tank differential pressure sensor terminal. The fuel tank differential pressure sensor terminal is grounded through the ECM terminal FPRE&ACTE.
  • The fuel tank differential pressure sensor terminal returns a voltage signal to the ECM terminal F/PR that is proportional to the pressure in the fuel tank.
 
 
TECHNICAL DESCRIPTION
  • The ECM monitors the fuel tank differential pressure sensor signal voltage.
  • The ECM determines whether the fuel tank differential pressure sensor signal voltage is within normal operating parameters.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • Detect malfunction if change of fuel tank differential pressure sensor output voltage during idling stays large during specified go/stop operations.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • Evaporative emission purge solenoid monitor
  • Evaporative emission ventilation solenoid monitor
  • Fuel temperature sensor monitor
  • Fuel level sensor monitor
Sensor (The sensors below are determined to be normal)
  • Mass airflow sensor
  • Engine coolant temperature sensor
  • Intake air temperature sensor
  • Barometric pressure sensor
  • Accelerator pedal position sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart (Monitor Sequence)
 
 
Check Conditions
  • Accelerator pedal is not depressed.
  • Vehicle speed is less than 1.5 km/h (1 mph).
    noteThe conditions for deviating from idling operation are as follows:
    • Vehicle speed is more than 50 km/h (31 mph).
Judgment Criteria
  • The drastic pressure fluctuation is detected 20 times or more per engine idling, which is that the fuel tank differential pressure sensor output voltage is 0.2 volt or more.
  • The condition described above is consecutively detected 4 times under the normal driving conditions.
    noteIf the number of sudden pressure fluctuations does not reach 20 times during any one period of engine idling, or if the ignition switch is turned OFF, the counter will reset to 0.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 15 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Fuel tank differential pressure sensor failed.
  • Fuel tank differential pressure sensor circuit harness damage or connector damage.
  • ECM failed.
 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool (M.U.T.-III), check data list item 52: Fuel Tank Differential Pressure Sensor.
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Disconnect the hose D from the evaporative emission canister.
(3) Plug the disconnected end of hose D.
(4) Turn the ignition switch to the "ON" position.
(5) Remove the fuel cap.
(6) Set scan tool (M.U.T.-III) to the data reading mode for item 52, Fuel Tank Differential Pressure Sensor.
  • Output voltage should be between 1,500 and 3,500 millivolts.
(7) Connect the evaporative emission system pressure pump (Miller number 6872A) to the fuel tank filler tube by using fuel tank adapter (MLR-8382) and pressurize the fuel tank.
  • The fuel tank pressure reading should increase.
(8) Turn the ignition switch to the "LOCK" (OFF) position.
(9) Remove the evaporative emission system pressure pump (Miller number 6872A) and the fuel tank adapter (MLR-8382), and reinstall the fuel cap.
(10) Connect hose D to the evaporative emission canister.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting / Inspection Service Points - How to Cope with Intermittent Malfunctions .
Go to Step 2.
 
STEP 2. Measure the sensor supply voltage at fuel tank differential pressure sensor connector by backprobing.
(1) Do not disconnect the connector.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal FPR5 line and ground by backprobing.
  • Voltage should be between 4.9 and 5.1 volts.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage between 4.9 and 5.1 volts?
Go to Step 4.
Go to Step 3.
 
STEP 3. Check of harness damage in FPR5 line between fuel tank differential pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 7.
Repair the connector(s) or wiring harness. Then go to Step 8.
 
STEP 4. Measure the ground voltage at fuel tank differential pressure sensor connector by backprobing.
(1) Do not disconnect the fuel tank differential pressure sensor connector.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal FPRE&ACTE line and ground by backprobing.
  • Voltage should be 0.5 volt or less.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage 0.5 volt or less?
Go to Step 6.
Go to Step 5.
 
STEP 5. Check of harness damage in FPRE&ACTE line between fuel tank differential pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 7.
Repair the connector(s) or wiring harness. Then go to Step 8.
 
STEP 6. Check of harness damage in F/PR line between fuel tank differential pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 7.
Repair the connector(s) or wiring harness. Then go to Step 8.
 
STEP 7. Replace the fuel tank differential pressure sensor.
(1) Replace the fuel tank differential pressure sensor.
(2) Carry out test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 15 .
(3) Check the diagnostic trouble code (DTC).
Is DTC P0451 set?
Replace the ECM (Refer to, Removal and Installation ). Then go to Step 8.
The inspection is complete.
 
STEP 8. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 15 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0451 set?
Retry the troubleshooting.
The inspection is complete.