P1451
2AZ-FXE ENGINE CONTROL SYSTEM: SFI SYSTEM: P1450-P1453: Fuel Tank Pressure Sensor
DTC P1450 - Fuel Tank Pressure Sensor
DTC P1451 - Fuel Tank Pressure Sensor Range/Performance
DTC P1452 - Fuel Tank Pressure Sensor Low Input
DTC P1453 - Fuel Tank Pressure Sensor High Input
DTC SUMMARY
DESCRIPTION
While the engine is running, if a predetermined condition (closed loop, etc.) is met, the purge VSV is opened by the ECM (included in hybrid vehicle control ECU) and stored fuel vapors in the canister are purged to the intake manifold. The ECM will change the duty cycle ratio of the purge VSV to control purge flow volume.
Purge flow volume is also determined by the intake manifold pressure. Atmospheric pressure is allowed into the canister through the vent valve to ensure that purge flow is maintained when negative pressure (vacuum) is applied to the canister.
The ECM monitors the condition of both the key-off monitor and purge flow monitor to ensure proper operation of the EVAP system.
Key-off monitor
This monitoring system checks for canister pump module malfunctions and leaks from the EVAP and closed tank systems. Be sure to leave the vehicle for at least 5 hours to sufficiently cool the fuel and stabilize fuel tank pressure. This makes EVAP system monitoring more accurate.
HINT: If the engine coolant temperature is 35°C (95°F) or more, 5 hours after the power switch has been turned off, the ECM will begin performing a monitor check after another 2 hours. If the engine coolant temperature is still 35°C (95°F) or more, 7 hours after the power switch has been turned off, the ECM will begin performing a monitor check after another 2.5 hours.
There are two methods for monitoring the EVAP system.
1. If the fuel tank pressure is higher or lower than the atmospheric pressure, the system determines that there are no leaks in the closed tank system and the system will check for leaks from the piping and canister between the purge VSV and canister pump module. (Method A)
2. If the fuel tank pressure is almost the same as the atmospheric pressure, vacuum pressure will enter the fuel tank and the system will check for leaks from the fuel tank after checking for leaks from the canister. (Method B)
HINT: *: If there is only a small amount of fuel in the fuel tank, stabilizing the EVAP pressure takes longer than usual.
Purge flow monitor
If EVAP system pressure change is less than 7.5 mmHg (1 kPa) when the engine is running and the purge VSV is turned ON (closed), the ECM determines that the purge flow is insufficient.
MONITOR DESCRIPTION
1. DTC P1451: Pressure sensor abnormal voltage fluctuation or being constant
If the pressure sensor output voltage fluctuates rapidly for 10 seconds, the ECM (included in the hybrid vehicle control ECU) stops the EVAP system monitor. The ECM interprets this as the pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC.
Alternatively, if the sensor output voltage does not change for 10 seconds, the ECM interprets this as the sensor voltage being constant, and stops the monitor. The ECM then illuminates the MIL and sets the DTC.
(Both the malfunctions are detected by 2-trip detection logic).
2. DTC P1452: Pressure sensor voltage low
If the pressure sensor output voltage is below 0.45 V, the ECM (included in the hybrid vehicle control ECU) interprets this as an open or short circuit malfunction in the pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (1-trip detection logic).
3. DTC P1453: Pressure sensor voltage high
If the pressure sensor voltage output is 4.9 V or more, the ECM (included in the hybrid vehicle control ECU) interprets this as an open or short circuit malfunction in the pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (1-trip detection logic).
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
P1451: (Noise Monitor)
Example of restart time:
P1451: (Stuck Monitor)
Example of restart time:
P1450, P1452 and P1453:
TYPICAL MALFUNCTION THRESHOLDS
1. P1450: Fuel tank pressure sensor
2. P1451: Pressure sensor noise
3. P1451: Pressure sensor stuck
4. P1452: Pressure sensor low voltage
5. P1453: Pressure sensor high voltage
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE:
- When a vehicle is brought into the workshop, leave it as it is. Do not change the vehicle condition. For example, do not tighten the fuel tank cap.
- Do not disassemble the pump module.
- The intelligent tester is required to conduct the following diagnostic troubleshooting procedure.
PROCEDURE
1. CONFIRM DTC AND FUEL TANK PRESSURE
(a) Connect the intelligent tester to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the tester on.
(d) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(e) Read the DTCs.
(f) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / EVAP / VAPOR PRESS TANK.
(g) Read the EVAP (Evaporative Emission) pressure displayed on the tester.
Result:
C -- GO TO EVAP INSPECTION PROCEDURE
B -- CHECK HARNESS AND CONNECTOR (VAPOR PRESSURE SENSOR - HV CONTROL ECU)
A -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (FUEL TANK PRESSURE SENSOR - HV CONTROL ECU)
(a) Turn the power switch off.
(b) Disconnect the A61 hybrid vehicle control ECU connector.
(c) Measure the resistance between the PTNK terminal of the hybrid vehicle control ECU connector and body ground.
Result:
(d) Reconnect the hybrid vehicle control ECU connector.
B -- REPLACE HYBRID VEHICLE CONTROL ECU
A -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (VAPOR PRESSURE SENSOR - HV CONTROL ECU)
(a) Remove the fuel tank assembly.
(b) Disconnect the N35 vapor pressure sensor connector.
(c) Disconnect the A61 hybrid vehicle control ECU connector.
(d) Measure the resistance between the PTNK terminal of the hybrid vehicle control ECU connector and body ground.
Result:
(e) Reconnect the pressure sensor connector.
(f) Reconnect the hybrid vehicle control ECU connector.
B -- REPAIR OR REPLACE HARNESS AND CONNECTOR
A -- REPLACE FUEL TANK PRESSURE SENSOR
4. CHECK HARNESS AND CONNECTOR (VAPOR PRESSURE SENSOR - HV CONTROL ECU)
(a) Remove the fuel tank assembly.
(b) Disconnect the N35 vapor pressure sensor connector.
(c) Turn the power switch on (IG).
(d) Measure the voltage and resistance according to the value(s) in the table below.
Standard:
Result:
(e) Reconnect the canister connector.
B -- REPAIR OR REPLACE HARNESS AND CONNECTOR
A -- Continue to next step.
5. REPLACE FUEL TANK PRESSURE SENSOR
NEXT -- CHECK WHETHER DTC OUTPUT RECURS (AFTER REPAIR)
6. REPAIR OR REPLACE HARNESS AND CONNECTOR
HINT: If the exhaust tail pipe has been removed, go to the next step before reinstalling it.
NEXT -- CHECK WHETHER DTC OUTPUT RECURS (AFTER REPAIR)
7. REPLACE HYBRID VEHICLE CONTROL ECU
NEXT -- CHECK WHETHER DTC OUTPUT RECURS (AFTER REPAIR)
8. CHECK WHETHER DTC OUTPUT RECURS (AFTER REPAIR)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the power switch on (IG) and turn the tester on.
(c) Wait for at least 60 seconds.
(d) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
HINT: If no pending DTC is displayed on the tester, the repair has been successfully completed.
NEXT -- COMPLETED