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Home >> Lexus >> 2006 >> GS 300 RWD V6-3.0L (3GR-FSE) >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0456

P0456

DTC P0455 Evaporative Emission Control System Leak Detected (Gross Leak)
DTC P0456 Evaporative Emission Control System Leak Detected (Very Small Leak)

Malfunction Detection Conditions:




DTC SUMMARY

DESCRIPTION







While the engine is running, if a predetermined condition (closed- loop etc.) is met, the EVAP VSV is opened by the ECM and stored fuel vapors in the canister are purged to the intake manifold. The ECM changes the duty cycle ratio of the EVAP VSV to control purge flow volume.

The 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 the purge flow is maintained when the negative pressure (vacuum) is applied to the canister. The following two monitors run to confirm appropriate EVAP system operation.

1. Key-off monitor
This monitor checks for Evaporative Emission (EVAP) system leaks and pump module malfunctions. The monitor starts 5 hours* after the engine switch is turned off. More than 5 hours are required to allow the fuel to cool down to stabilize the Fuel Tank Pressure (FTP), thus making the EVAP system monitor more accurate.
The electric vacuum pump creates negative pressure (vacuum) in the EVAP system and the pressure is measured. Finally, the ECM monitors for leaks from the EVAP system and malfunctions in both the pump module and EVAP VSV, based on the EVAP pressure.

HINT:
*: If the engine coolant temperature is not below 35 degrees C 5 hours after the engine switch is turned off, the monitor check starts 2 hours later. If it is still not below 35 degrees C 7 hours after the engine switch is turned off, the monitor check starts 2.5 hours later.














2. Purge flow monitor
The purge flow monitor consists of the two monitors. The 1st monitor is conducted every time and the 2nd monitor is conducted if necessary.
- The 1st monitor
While the engine is running and the purge Vacuum Switching Valve (VSV) is ON (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd monitor.
- The 2nd monitor
The vent valve turned OFF (open) and the EVAP pressure is then measured. If the variation in the pressure is less than 0.5 kPa (3.75 mmHg), the ECM interprets this as the EVAP VSV being stuck closed, and illuminates the MIL and sets DTC P0441 (2 trip detection logic).

Atmospheric pressure check:
In order to ensure reliable malfunction detection, the variation between the atmospheric pressures, before and after conduction of the purge flow monitor, is measured by the ECM.

Wiring Diagram (Part 1):




Wiring Diagram (Part 2):






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INSPECTION PROCEDURE


NOTE: The intelligent tester is required to conduct the following diagnostic troubleshooting procedure.

HINT:
- Using the intelligent tester monitor results enable the EVAP system to be confirmed.
- Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

MONITOR DESCRIPTION










Monitor Strategy:




Typical Enabling Conditions (Part 1):




Typical Enabling Conditions (Part 2):




Typical Malfunction Thresholds:




5 hours* after the engine switch is turned to off, the electric vacuum pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

HINT:
*: If the engine coolant temperature is not below 35 degrees C (95 degrees F) 5 hours after the engine switch is turned off, the monitor check starts 2 hours later. If it is still not below 35 degrees C (95 degrees F) 7 hours after the engine switch is turned off, the monitor check starts 2.5 hours later.


HINT:
*: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.

1. P0455: EVAP (Evaporative Emission ) gross leak
In operation C, the vacuum pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than [second 0.02 inch leak pressure standard x 0.2], (near atmospheric pressure), the ECM determines that EVAP system has a large leakage, illuminates the MIL and sets the DTC (2 trip detection logic).

2. P0456: EVAP very small leak
In operation C, the vacuum pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than second 0.02 inch leak pressure standard, the ECM determines that the EVAP system has a small leakage, illuminates the MIL and sets the DTC (2 trip detection logic).

MONITOR RESULT

Detailed information on Monitor Result. Checking Monitor Status
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