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DTC P1451: Bypass Valve Stuck Closed
 
 
 
 
CIRCUIT OPERATION
  • Refer to DTC P1445 - Bypass Valve Circuit Low Input .
 
 
TECHNICAL DESCRIPTION
  • During the key-off evaporative leakage monitoring, when fuel tank pressure cannot be reduced by actuating the evaporative emission leak detection pump during the fuel tank solenoid valve opening instruction, it is judged as bypass valve stuck close.
 
 
MONITOR EXECUTION
  • Once per driving cycle.
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • 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 sensor below is determined to be normal)
  • Engine coolant temperature sensor
  • Intake air temperature sensor
 
 
DTC SET CONDITIONS
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.
  • Fuel tank pressure at ECM wake-up is less than 19.96 kPa (5.89 in.Hg) or more than 40.00 kPa (11.81 in.Hg).
Judgment Criteria
  • The fuel tank absolute pressure subtracted from the barometric pressure measured by the fuel tank pressure sensor is less than 1.04 kPa (0.307 in.Hg).
  • The fuel tank pressure subtracted from the barometric pressure measured by the fuel tank differential pressure sensor is less than 1.00 kPa (0.295 in.Hg).
  • The canister pressure is less than following pressure: 0.985 kPa (0.2909 in.Hg) subtracted from the first reference pressure.
  • The canister pressure subtracted from the barometric pressure is more than 0.985 kPa (0.2909 in.Hg) while the valve of the evaporative emission purge solenoid is open.
 
 
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 4 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Bypass valve stuck close.
  • Evaporative emission canister is clogged.
  • Shorted bypass valve circuit 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 DTC P1445 or P1446 set?
Refer to DTC P1445 - Bypass Valve Circuit Low Input , DTC P1446 - Bypass Valve Circuit High Input .
Go to Step 2.
 
STEP 2. Replace the bypass valve (integrated in evaporative emission canister).
(1) Replace the bypass valve (integrated in evaporative emission canister).
(2) Carry out an evaporative emission system monitor. Refer to Evaporative Emission System Monitor Test .
(3) Check the item 216, Bypass Valve Stuck Closed 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 3.
 
STEP 3. 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 4 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P1451 set?
Retry the troubleshooting.
The inspection is complete.