- DTC judgment completed
- System normal
Lexus NX: Evaporative Emission Control System Leak Detected (Gross Leak) (P0455,P0456)
Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (engine Control) / Sfi System / Evaporative Emission Control System Leak Detected (Gross Leak) (P0455,P0456)
DTC SUMMARY
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory |
|---|---|---|---|---|---|
| P0455 | Evaporative Emission Control System Leak Detected (Gross Leak) | Leak detection pump creates negative pressure (vacuum) in EVAP system and EVAP system pressure is measured. Reference pressure is measured at start and end of leak check. If stabilized pressure is higher than [second reference pressure x 0.2], ECM determines that EVAP system has a large leak. |
| Comes on | DTC stored |
| P0456 | Evaporative Emission Control System Leak Detected (Very Small Leak) | Leak detection pump creates negative pressure (vacuum) in EVAP system and EVAP system pressure is measured. Reference pressure is measured at start and end of leak check. If stabilized pressure is higher than second reference pressure, ECM determines that EVAP system has a small leak. |
| Comes on | DTC stored |
| DTC No. | Monitoring Item | Detection Timing | Detection Logic |
|---|---|---|---|
| P0455 | EVAP gross leak | While power switch off | 2 trip |
| P0456 | EVAP small leak | While power switch off | 2 trip |
DESCRIPTION
The description can be found in EVAP (Evaporative Emission) System.
Click here .gif)
MONITOR DESCRIPTION
5 hours* after the power switch is turned off, the leak detection 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 less than 35°C (95°F) 5 hours after the power switch is turned off, the monitor check starts 2 hours later. If it is still not less than 35°C (95°F) 7 hours after the power switch is turned off, the monitor check starts 2.5 hours later.
| Sequence | Operation | Description | Duration |
|---|---|---|---|
| - | ECM activation | Activated by soak timer 5, 7 or 9.5 hours after power switch turned off. | - |
| A | Atmospheric pressure measurement | Vent valve is turned off (vent) and EVAP system pressure is measured by ECM in order to register atmospheric pressure. If pressure in EVAP system is not between 70 kPa(abs) and 111 kPa(abs) [525 mmHg(abs) and 836 mmHg(abs)], ECM cancels EVAP system monitor. | 60 seconds |
| B | First reference pressure measurement | In order to determine reference pressure, leak detection pump creates negative pressure (vacuum) through reference orifice and then ECM checks if leak detection pump and vent valve operate normally. | 360 seconds |
| C | EVAP system pressure measurement | Vent valve is turned on (closed) to shut EVAP system. Negative pressure (vacuum) is created in EVAP system, and EVAP system pressure is then measured. Write down measured value as it will be used in leak check. If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor. | 15 minutes* |
| D | Purge VSV monitor | Purge VSV is opened and then EVAP system pressure is measured by ECM. Large increase indicates normal. | 10 seconds |
| E | Second reference pressure measurement | After second reference pressure measurement, leak check is performed by comparing first and second reference pressure measurements. If stabilized system pressure is higher than second reference pressure, ECM determines that EVAP system is leaking. | 60 seconds |
| - | Final check | Atmospheric pressure is measured and then monitoring result is recorded by ECM. | - |
*: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.
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| *1 | Purge VSV: Off (Closed) | *2 | Purge VSV: On (Open) |
| *3 | Vent Valve: Off (Vent) | *4 | Vent Valve: On (Closed) |
| *5 | Leak Detection Pump: Off | *6 | Leak Detection Pump: On |
| *7 | Reference Orifice (0.02 inch) | *8 | Canister Pressure Sensor |
| *9 | Canister | *10 | Fuel Tank |
| *11 | Canister Pump Module | *12 | Canister Filter |
| *a | Operation A: Atmospheric Pressure Measurement | *b | Operation B, E: Reference Pressure Measurement |
| *c | Operation C: EVAP System Pressure Measurement | *d | Operation D: Purge VSV Monitor |
| *e | Atmospheric Pressure | *f | Negative Pressure |
-
(a) P0455: EVAP (Evaporative Emission) gross leak
In operation C, the leak detection 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 reference pressure x 0.2] (near atmospheric pressure), the ECM determines that the EVAP system has a large leak, illuminates the MIL and stores the DTC (2 trip detection logic).
-
(b) P0456: EVAP very small leak
In operation C, the leak detection 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 reference pressure, the ECM determines that the EVAP system has a small leak, illuminates the MIL and stores the DTC (2 trip detection logic).
MONITOR STRATEGY
| Required Sensors/Components (Main) | Purge VSV Canister pump module |
| Required Sensors/Components (Related) | - |
| Frequency of Operation | Once per driving cycle |
| Duration | Within 20 minutes (varies with amount of fuel in tank) |
| MIL Operation | 2 driving cycles |
| Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
| Monitor runs whenever the following DTCs are not stored | None |
| Atmospheric pressure | 70 kPa(abs) [525 mmHg(abs)] or higher, and less than 111 kPa(abs) [836 mmHg(abs)] |
| Auxiliary battery voltage | 10.5 V or higher |
| Vehicle speed | Less than 4 km/h (2.5 mph) |
| Power switch | Off |
| Time after key-off | 5, 7 or 9.5 hours |
| Canister pressure sensor malfunction (P0452, P0453) | Not detected |
| Purge VSV | Not operated by scan tool |
| Vent valve | Not operated by scan tool |
| Leak detection pump | Not operated by scan tool |
| Both of the following conditions met before-key off | Conditions 1 and 2 |
| 1. Duration that vehicle is driven | 5 minutes or more |
| 2. EVAP purge operation | Performed |
| Engine coolant temperature | 4.4°C (40°F) or higher, and less than 35°C (95°F) |
| Intake air temperature | 4.4°C (40°F) or higher, and less than 35°C (95°F) |
TYPICAL MALFUNCTION THRESHOLDS
P0455: EVAP Gross Leak| EVAP pressure when vacuum introduction is complete | Higher than [reference pressure x 0.2] |
| EVAP pressure when vacuum introduction is complete | Between reference pressure and [reference pressure x 0.2] |
MONITOR RESULT
Refer to EVAP System.
Click here
CONFIRMATION DRIVING PATTERN
NOTICE:
- The Evaporative System Check (Automatic Mode) consists of 6 steps performed automatically by the Techstream. It takes a maximum of approximately 24 minutes.
- Do not perform the Evaporative System Check when the fuel tank is more than 85% full because the cut-off valve may be closed, making the fuel tank leak check unavailable.
- Do not run the engine during this operation.
- When the temperature of the fuel is 35°C (95°F) or higher, a large amount of vapor forms and any check results become inaccurate. When performing the Evaporative System Check, keep the fuel temperature less than 35°C (95°F).
- Connect the Techstream to the DLC3.
- Turn the power switch on (IG) and turn the Techstream on.
- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
- Turn the power switch off and wait for at least 30 seconds.
- Turn the power switch on (IG) and turn the Techstream on.
- Enter the following menus: Powertrain / Engine and ECT / Utility / Evaporative System Check / Automatic Mode.
- After the Evaporative System Check is completed, check for All Readiness by entering the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
- Input the DTC: P0455 or P0456.
-
Check the DTC judgment result.
Techstream Display
Description
NORMAL
ABNORMAL
- DTC judgment completed
- System abnormal
INCOMPLETE
- DTC judgment not completed
- Perform driving pattern after confirming DTC enabling conditions
N/A
- Unable to perform DTC judgment
- Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
HINT:
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows ABNORMAL, the system has a malfunction.
-
If the judgment result is INCOMPLETE or N/A and no pending DTC is output, perform a universal trip and check for permanent DTCs.
Click here
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
PROCEDURE
| 1. | GO TO EVAP SYSTEM |
(a) Refer to EVAP System.
Click here
| NEXT | .gif) | END |
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