P0455

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

CIRCUIT DESCRIPTION

The vapor pressure sensor, CCV and Pressure switching valve 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 P0442, P0455 or P0456 is recorded in the ECM when evaporative emissions leak from the components within the dotted line in Fig, or when the vapor pressure sensor malfunctions.

DTC Detection Condition:

HINT: Refer to DTCs P0441, P0446 and P2418.

HINT: Typical DTC output of each trouble is shown.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions Part 1:

Typical Enabling Conditions Part 2:

Typical Malfunction Thresholds:

Monitor Result:

A leak in the evaporative emission system directs 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 EVAP VSV to open while the CCV (vent) is closed. After sufficient time has elapsed, the fuel tank should have developed a high negative pressure (vacuum) and the EVAP VSV should be 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 the system has a leak.The ECM will turn on the MIL and set a DTC. The ECM sets the following DTCs for small and large leaks:

1. DTC P0442 is set when the internal fuel tank pressure has a large increase and the EVAP system has a small leak.
2. DTC P0455 is set when the EVAP system has a very large leak. Even though the ECM sends a signal to the EVAP VSV (when CCV is closed) to create a vacuum, the internal fuel tank pressure does not decrease beyond a specified level.
3. DTC P0456 is set when the internal fuel tank pressure increases slightly and the EVAP system has a small leak.

CONFIRMATION READINESS TEST

First Trip Procedure

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

c. Clear DTCs.
- Disconnect the battery terminals or EFI fuse for more than 60 seconds.
- READINESS TESTS will show INCMPL (incomplete).

d. Drive the vehicle on a freeway. Write down 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 NONCONTINUOUS TESTS screen.

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

- To get there, go to Advanced OBD II, Onboard 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 in the ECM

If the EVAP evaluation monitor shows INCMPL, go to the NONCONTINUOUS TESTS 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 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 where first trip DTC's are listed.

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

Second Trip Procedure

a. The vehicle must be cold, and the ambient temperature is between approximately 10 °C (50 °F) and 35 °C (95 °F).
b. Go to READINESS TESTS screen.
c. Drive the vehicle on a freeway. Write down the state of the 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 DTCs.
- If a DTC Is stored, the problem has been detected and confirmed by the ECM.
- If no DTC Is found, the EVAP monitor has operated but no problem Is detected.

Wiring Diagram:

INSPECTION PROCEDURE

HINT:
- If DTC P0441 (Purge Flow), P0446 (CCV or 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 is turned 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 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.
- When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the vapor pressure sensor.