P0455, P0456

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

DTC SUMMARY

DTC No.	Monitoring Item	Malfunction Detection Condition	Trouble Area	Detection Timing	Detection Logic
P0455	EVAP 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.	Fuel cap (loose) Leakage from EVAP line (canister - fuel tank) Leakage from EVAP line (purge VSV - canister) Leakage from canister pump module Leakage from fuel tank Leakage from canister	While power switch off	2 trip
P0456	EVAP small leak	Leak detection pump creates negative pressure (vacuum) in EVAP system and EVAP system pressure is measured. Reference pressure 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.	While power switch off	2 trip

DTC No.

Monitoring Item

Malfunction Detection Condition

Trouble Area

Detection Timing

Detection Logic

P0455

EVAP 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.

Fuel cap (loose)
Leakage from EVAP line (canister - fuel tank)
Leakage from EVAP line (purge VSV - canister)
Leakage from canister pump module
Leakage from fuel tank
Leakage from canister

While power switch off

2 trip

P0456

EVAP small leak

Leak detection pump creates negative pressure (vacuum) in EVAP system and EVAP system pressure is measured. Reference pressure 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.

While power switch off

2 trip

DESCRIPTION

The circuit description can be found in EVAP (Evaporative Emission) System Click here.

MONITOR DESCRIPTION

5 hours* after the power switch is turned off, the leak detection pump creates negative pressure (vacuum) in the EVAP system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

Tech Tips

*: 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 110 kPa(abs) [525 mmHg(abs) and 825 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.

Text in Illustration
*1	Operation A: Atmospheric Pressure Measurement	*2	Purge VSV: OFF
*3	Reference Orifice	*4	Canister
*5	Fuel Tank	*6	Vent Valve: OFF (vent)
*7	Canister Pump Module	*8	Canister Pressure Sensor
*9	Canister Filter	*10	Leak Detection Pump: OFF
*11	Operation B, E:	*12	Reference Leak Pressure Measurement
*13	OFF	*14	OFF (vent)
*15	ON	*16	Reference Orifice (0.02 inch)
*17	Operation C: EVAP System Pressure Measurement	*18	OFF
*19	ON (closed)	*20	ON
*21	Atmospheric Pressure	*22	Negative Pressure
*23	Operation D: Purge VSV Monitor	*24	ON
*25	ON	*26	ON (closed)

(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	Purge VSV and canister pump module
Frequency of Operation	Once per driving cycle

CONFIRMATION DRIVING PATTERN

Note

The Evaporative System Check (Automatic Mode) consists of 6 steps performed automatically by the GTS. It takes a maximum of approximately 18 minutes.
Do not perform the Evaporative System Check when the fuel tank is more than 90% 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 GTS to the DLC3.
Turn the power switch on (IG) and turn the GTS 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 GTS 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.

GTS Display	Description
NORMAL	DTC judgment completed System 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

Tech Tips

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.

INSPECTION PROCEDURE

Refer to the EVAP System Click here.

SFI SYSTEM, Diagnostic DTC:P0455, P0456