P1451

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

DTC Detection Condition:

DESCRIPTION
While the engine is running, if a predetermined condition (closed loop, etc.) is met, the EVAP VSV is opened by the ECM (Included in HV 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 EVAP 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 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 or more, 5 hours after the ignition switch has been turned off, the ECM (Included in HV control ECU) will begin performing a monitor check after another 2 hours. If the engine coolant temperature is still 35°C or more, 7 hours after the ignition 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 EVAP VSV and 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)














Purge flow monitor




If EVAP system pressure change is less than 7.5 mmHg (1 kPa) when the engine is running and the EVAP VSV is turned ON (closed), the ECM (Included in HV control ECU) 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 HV 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 HV control ECU) interprets this as an open or short circuit 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 HV control ECU) interprets this as an open or short circuit 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 (Part 1):

Typical Malfunction Thresholds:

Wiring Diagram:

INSPECTION PROCEDURE

NOTE:
- 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.

Step 1:

Step 2:

Step 3:

Step 4-7:

Step 8: