[Previous][Next]
DTC P1451-73: Bypass valve stuck closed
 
 
 
 
CIRCUIT OPERATION
  • Bypass valve is built into the evaporative emission canister (main).
  • MFI relay is built into the IPDM E/R.
  • The bypass valve power is supplied from the MFI relay.
  • The ECM controls bypass valve by turning the power transistor in the ECM "ON" and "OFF".
 
 
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 battery positive voltage is 11.0 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 percent 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).
  • Accumulated time that power supply mode of electric motor switch is ON is more than 27 minutes.
Judgment Criteria
  • The fuel tank absolute pressure subtracted from the barometric pressure measured by the fuel tank pressure sensor is less than specified pressure for 180 seconds.
  • The fuel tank pressure subtracted from the barometric pressure measured by the fuel tank differential pressure sensor is less than specified pressure for 180 seconds.
  • The canister pressure subtracted from the barometric pressure is more than specified pressure for 180 seconds while the valve of the evaporative emission purge solenoid is open.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Prohibit introduction of purges.
  • Fuel filler lid cannot be opened even when pressing the fuel filler 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 OBD- II DRIVE CYCLE.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Bypass valve [built into the evaporative emission canister (main)] stuck close.
  • Shorted bypass valve circuit 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
1.STEP 1. Using scan tool (M.U.T.-III SE), read the DTC.
Use scan tool (M.U.T.-III SE) to check and see if a DTC P1445-14 or P1446-12 is set.
Q: Is DTC P1445-14 or P1446-12 is set. set?
Perform troubleshooting for the bypass valve circuit (Refer to DTC P1445-14: EVAP System Bypass Solenoid Valve Circuit Low DTC P1445-14: EVAP System Bypass Solenoid Valve Circuit Low, and Refer to DTC P1446-12: EVAP System Bypass Solenoid Valve Circuit High DTC P1446-12: EVAP System Bypass Solenoid Valve Circuit High).
 
2.STEP 2. Check harness between bypass valve connector terminal number 1 and ECM connector terminal number 66.
Check output line for damage.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
3.STEP 3. Check harness between IPDM E/R connector terminal number 78 and bypass valve connector terminal number 2.
Check power supply line for damage.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
4.STEP 4. Using scan tool (M.U.T.-III SE) to check the data list, after replace evaporative emission canister (main) and perform the evaporative emission system monitor test.
(1) Replace the evaporative emission canister (main) (integrated with bypass valve) (Refer to ENGINE, Engine, Motor and Emission Control – Emission Control – Evaporative Emission System FUEL TANK SOLENOID VALVE REPLACEMENT).
(2) Perform the evaporative emission system monitor test (Refer to EVAPORATIVE EMISSION CONTROL SYSTEM MONITOR TEST).
(3) Use scan tool (M.U.T.-III SE) to check the data list (Refer to DATA LIST REFERENCE TABLE).
  • Item number 520: Bypass valve stuck closed NG
Q: Is the check result normal?
The inspection is complete.
Replace the ECM (Refer to ENGINE CONTROL MODULE (ECM) REMOVAL AND INSTALLATION).