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DTC P0451: Evaporative Emission System Pressure Sensor Range/Performance
 
 
 
 
CIRCUIT OPERATION
  • The ECM terminal FDP5 supplies a 5 volts reference signal to the fuel tank differential pressure sensor. The fuel tank differential pressure sensor is grounded through the ECM terminal FDPE.
  • The fuel tank differential pressure sensor returns a voltage signal to the ECM terminal FDPS that is proportional to the pressure in the fuel tank.
 
 
TECHNICAL DESCRIPTION
  • The ECM monitors the fuel tank differential pressure sensor output 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 the fuel tank differential pressure sensor output value is out of specified range during refuel control mode or key-off evaporative leakage monitoring.
 
 
MONITOR EXECUTION
  • Once per refueling <Rationality - low>
  • Once per driving cycle <Rationality - high/low>
 
 
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC set in memory for the item monitored below) <Rationality - low>
  • Bypass valve monitor
  • Fuel tank solenoid valve monitor
  • Switching valve monitor
  • Fuel tank differential pressure sensor monitor
  • Evaporative emission purge system monitor
Sensor (The sensors below are determined to be normal) <Rationality - low>
  • Bypass valve
  • Fuel tank solenoid valve
  • Switching valve
  • Fuel tank differential pressure sensor
Other Monitor (There is no temporary DTC set in memory for the item monitored below) <Rationality - high/low>
  • Evaporative emission purge solenoid monitor
  • Bypass valve monitor
  • Fuel tank solenoid valve monitor
  • Switching valve monitor
  • Canister pressure sensor monitor
  • Manifold absolute pressure sensor monitor
  • Fuel tank pressure sensor monitor
  • Fuel tank differential pressure sensor monitor
  • Barometric pressure sensor/Manifold absolute pressure correlation
  • Barometric pressure sensor monitor
  • Fuel level sensor monitor
  • Engine off timer monitor
  • Controller area network (CAN) monitor
Sensor (The sensors below are determined to be normal) <Rationality - high/low>
  • Engine coolant temperature sensor
  • Intake air temperature sensor
 
 
DTC SET CONDITIONS <Rationality - low>
Logic Flow Chart
Check Conditions
  • 12V starter battery positive voltage is between 10 and 16.5 volts.
  • During the refuel control mode.
  • Fuel filler lid is closed.
Judgment Criterion
  • When the fuel tank differential pressure outputs less than atmospheric pressure during decompression of fuel tank by pressing the fuel filler lid opener switch.
 
 
DTC SET CONDITIONS <Rationality - high/low>
Logic Flow Chart
Check Conditions
  • Power supply mode of electric motor switch is OFF.
  • 12V starter battery positive voltage is 11 volts or higher.
  • Engine coolant temperature is higher than 4°C (39°F) and lower than 35°C (95°F).
  • Intake air temperature at ECM wake-up is higher than 4°C (39°F) and lower than 35°C (95°F).
  • ECM is woken up in 5, 6 or 8.5 hours since the power supply mode of electric motor switch was OFF.
  • Barometric pressure is 76 kPa (22.4 in.Hg) or higher.
  • Fuel level is 85% or less.
  • The fuel tank pressure is less than 20 kPa (5.9 in.Hg) or more than 40 kPa (11.8 in.Hg).
Judgment Criteria
  • Barometric pressure measured by the fuel tank differential pressure sensor is out of specified range.
  • The fuel tank absolute pressure subtracted from the barometric pressure measured by the fuel tank pressure sensor is more than specified pressure.
  • The fuel tank pressure subtracted from the barometric pressure measured by the fuel tank differential pressure sensor is more than specified pressure.
  • The canister pressure is less than specified pressure.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Fuel filler lid cannot be opened even when pressing the fuel filler lid opener switch.
  • Indicates "REFUELING SYSTEM SERVICE REQUIRED" on the information screen in the multi-information display.
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
 
 
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
STEP 1. Using scan tool (M.U.T.-IIISE), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Turn on the power supply mode of the electric motor switch.
(3) Read the DTC.
(4) Turn off the power supply mode of the electric motor switch.
Is the diagnostic trouble code other than P0451 set?
Refer to, Diagnostic Trouble Code Chart .
Go to Step 2.
 
STEP 2. Using scan tool (M.U.T.-IIISE), check data list item 210: Fuel Tank Differential Pressure Sensor.
(1) Disconnect the hose D from the bypass valve.
(2) Plug the disconnected end of hose D.
(3) Turn on the power supply mode of the electric motor switch.
(4) Remove the fuel cap.
(5) Set scan tool (M.U.T.-IIISE) to the data reading mode for item 210, Fuel Tank Differential Pressure Sensor.
  • The standard value should be -0.57 to 0.57 kPa (-0.168 to 0.168 in.Hg).
(6) 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 in the range of 30 kPa (8.9 in. Hg) or less.
  • The fuel tank pressure reading should increase.
(7) Turn off the power supply mode of the electric motor switch.
(8) Remove the evaporative emission system pressure pump (Miller number 6872A) and the fuel tank adapter (MLR-8382), and reinstall the fuel cap.
(9) Connect hose D to the bypass valve.
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 3.
 
STEP 3. Check of harness damage in FDP5, FDPE and FDPS line between fuel tank differential pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 4.
Repair the connector(s) or wiring harness. Then go to Step 5.
 
STEP 4. Replace the fuel tank differential pressure sensor.
(1) Replace the fuel tank differential pressure sensor.
(2) Carry out an evaporative emission system monitor. Refer to Evaporative Emission System Monitor Test .
(3) Check the item 218, Tank Differential Pressure Sensor Shift in the data list.
(4) Turn off the power supply mode of the electric motor switch.
Is the data list "Normal"?
The inspection is complete.
Replace the ECM (Refer to Removal and Installation ). Then go to Step 5.
 
STEP 5. Perform 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 1 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0451 set?
Retry the troubleshooting.
The inspection is complete.