P0456

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

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The vapor pressure sensor and VSV for vapor pressure sensor are used to detect abnormalities in the evaporative emission control system.

The ECM decides whether there is an abnormality in the evaporative emission control system based on the vapor pressure sensor signal.

DTC P0440 is recorded by the ECM when evaporative emissions leak from the components within the dotted line in Fig. 1, or when the vapor pressure sensor malfunctions.

HINT: Typical DTC output of each trouble part

Wiring Diagram:

CONFIRMATION READINESS TEST

First Trip Procedure
a. Vehicle must be cold, ambient temperature approximately between 10 °C (50 °F) - 35 °C (950 °F).
b. Intake Air Temp. (IAT) and Engine Coolant Temp. (ECT) sensor almost same value.

c. Clear DTC's.
- Disconnecting the battery terminals or EFI fuse.
- Readiness tests will show INCMPL (incomplete).

d. Drive the vehicle according to LA#4 drive cycle. Note the state of Readiness Tests. They will change to COMPL as the evaluation monitors operate and if the system passes. This procedure may take approximately 20 minutes or more.

NOTE: Do not shut off the engine - the results will be invalid.

Pass Condition - No Problem Found by the ECM

If the EVAP evaluation monitor shows COMPL, go to the Non- Continuous Test screen.

NOTE: Do not shut off the engine - the results will be invalid.

- To get there, go to Advanced OBD II, On-board Tests, Non-continuous Tests.
- If all of the tests in the time $02 category Tests show Pass, the evaluation monitor has operated and no problem was detected.

Fail Condition - Problem Detected by the ECM

If the EVAP evaluation monitor shows INCMPL, go to the Non- Continuous Test screen.

1. If all Tests show Pass, the following may have occurred.
- The EVAP evaluation monitor did not operate.
- The EVAP evaluation monitor did not finish.
- The ECM withheld judgement.

2. If one or more of the tests in the time $02 category show Fail, the EVAP evaluation monitor did operate and the ECM detected a problem.

3. Go to Continuous Tests screen. This is the only place DTC's are listed for the first trip.

NOTE: The DTC listed may not be valid. A second trip is needed to confirm the DTC.

Second Trip Procedure

a. Vehicle must be cold, ambient temperature approximately between 10 °C (50 °F) - 35 °C (95 °F).
b. Go to Readiness Tests screen.
c. Drive the vehicle according to LA#4 drive cycle. Note the state of EVAP evaluation monitor. This procedure may take approximately 20 minutes or more.

NOTE: Do not shut off the engine - the results will be invalid.

If Readiness Tests changes to COMPL, the EVAP evaluation monitor has operated. Check for any stored DTC's.
- If a DTC has stored, the problem has been detected and confirmed by the ECM.
- If no DTC was found, the EVAP monitor operated but no problem was detected.

INSPECTION PROCEDURE

HINT:
- If DTC P0441 (Purge Flow), P0446 (VSV for CCV or VSV for Pressure switching valve) or P0451 (Evaporative Pressure Sensor) is output with DTC P0442 or P0456, first troubleshoot DTC P0441, P0446 or P0451. If no malfunction is detected, troubleshoot DTC P0442 or P0456 next.
- Ask the customer whether, after the MIL came on, the customer found the fuel tank cap loose and tightened it. Also ask the customer whether the fuel tank cap was loose when refuelling. If the fuel tank cap was loose, it was the cause of the DTC. If the fuel tank cap was not loose or if the customer was not sure if it was loose, troubleshoot according to the following procedure.
- Read freeze frame data using OBD II scan tool or hand-held tester. Because freeze frame records the engine conditions when the malfunction is detected. When troubleshooting, it is useful to determine whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
- When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the vapor pressure sensor.