DTC P0455 Evaporative Emission Control System Leak Detected (Gross Leak)

DTC P0455 EVAPORATIVE EMISSION CONTROL SYSTEM LEAK DETECTED (GROSS LEAK)

MONITOR DESCRIPTION

DTC Detection Condition:

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

Monitor Result (Mode 06 Data):

The ECM tests the Evaporative Emissions (EVAP) system using the fuel tank pressure sensor, the Canister Close Valve (CCV), and the VSV for EVAP. The ECM closes the EVAP system and introduces a negative pressure (vacuum) into it. The ECM then monitors the internal pressure using the fuel tank pressure sensor (Refer to the diagram leak check).

P0455
A leak in the evaporative emission system prompts the ECM to set DTC P0442, P0455 or P0456. The ECM checks for leaks in the system by introducing a high negative pressure (vacuum) from the intake manifold by commanding the VSV for EVAP open while the VSV for CCV (vent) is closed. After sufficient time has elapsed the fuel tank should develop a high negative pressure (vacuum) and the VSV for EVAP is closed. The ECM then monitors the pressure-rise (loss of vacuum) in the fuel tank. If the pressure rises too rapidly, the ECM concludes that there is a leak in the system.
The ECM will turn on the MIL and a DTC is set.

The ECM has separate DTCs for small and large leaks:
a. DTC P0442 is set when the internal fuel tank pressure has a large increase and the EVAP system has a small leak.
b. DTC P0455 is set when EVAP system has a very large leak. Even though the ECM sends a signal to the VSV for EVAP when CCV is closed to create a vacuum when CCV is closed, the internal fuel tank pressure does not decrease beyond a specified level.
c. DTC P0456 is set when the internal fuel tank pressure increase slightly and the EVAP system has a very small leak.

CONFIRMATION READINESS TEST

First Trip Procedure
a. The vehicle must be cold and the ambient temperature must be approximately between 10 to 35 °C (50 to 95 °F).
b. The Intake Air Temperature (IAT) and the Engine Coolant Temperature (ECT) sensors indicate almost the same value.

c. Clear the DTCs.
Disconnect the battery terminal or remove the EFI and ETCS fuses for more than 60 seconds.
READINESS TESTS will show INCMPL (incomplete).
d. Drive the vehicle on a freeway. Write down the initial status of the READINESS TESTS. As each Readiness Test passes EVAP evaluation monitors, its status will change to COMPL (complete). 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 TESTS screen.

Enter the following menus: ADVANCED OBD II/ ON-BOARD TESTS/NON-CONTINUOUS.

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

If all of the tests in the "Time $02" category show "Pass", the EVAP evaluation monitor detected no problem.

Fail Condition - Problem Detected by the ECM
If the EVAP evaluation monitor shows COMPL, go to the NON- CONTINUOUS TESTS screen.

1. If all tests show "Pass", one of the following may have occurred:
The EVAP evaluation monitor did not operate.
The EVAP evaluation monitor did not finish its tests.
The ECM has 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 the CONTINUOUS TESTS screen. This is the only place DTCs are listed for the first trip.

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

Second Trip Procedure

e. The vehicle must be cold, and the ambient temperature must be approximately between 50 to 95 °F.
f. Go to the READINESS TESTS screen.
g. Drive the vehicle on a freeway. Write down the initial status of the READINESS TESTS. This procedure may take approximately 20 minutes or more.

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

h. If the READINESS TESTS change to COMPL, the EVAP evaluation monitor has operated. Check for any stored DTCs.
If a DTC was 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.

Wiring Diagram:

INSPECTION PROCEDURE

HINT:
When using the hand-held tester, follow the procedures under the title "Hand-held tester".

When using the OBD II scan tool, follow the procedures under the title "OBD II scan tool (excluding hand-held tester)" (see the procedures after the "Hand-held tester" procedures).

Always troubleshoot DTCs P0441 (purge flow), P0446 (VSV for CCV), P0451, P0452 and P0453 (evaporative pressure sensor) before troubleshooting DTCs P0442 or P0456.

As the customer the following questions:
1. When the MIL came on, if the fuel tank cap was loose and if it was then tightened.
2. When refueling, if the fuel tank cap was loose.

If the fuel tank cap was loose, that is the why the DTC was stored.

If the fuel cap was not loose or if the customer cannot remember, troubleshoot according to the procedures.

Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.

If the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the vapor pressure sensor.