P0455

DTC P0455 Evaporative Emission System Leak Detected (Gross Leak)

Circuit Description
The Evaporative (EVAP) Emission system includes the following components:
- Fuel tank
- EVAP Emission vent solenoid
- Fuel tank pressure sensor
- Fuel pipes and hoses
- Fuel vapor lines
- Fuel cap
- EVAP Emission canister
- Purge lines
- EVAP Emission canister purge valve
- EVAP Emission service port

The EVAP emission system is checked by applying vacuum to the EVAP emission system and monitoring for a vacuum decay. The engine control module (ECM) monitors the vacuum level through the fuel tank pressure sensor signal.

At the appropriate time, the EVAP emission canister purge valve and the EVAP emission vent solenoid are turned ON, allowing the engine to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP emission canister purge valve is turned OFF, sealing the system. If a sufficient vacuum level cannot be achieved, a large leak is indicated. This can be caused by the following conditions:
- Missing or faulty fuel cap.
- Disconnected or faulty fuel tank pressure sensor.
- Disconnected, damaged, pinched, or blocked EVAP emission purge line
- Disconnected or faulty EVAP emission canister purge valve.
- Disconnected or faulty EVAP emission vent solenoid.
- Open ignition feed circuit to the EVAP emission vent or purge solenoid.
- Damaged EVAP emission canister.
- Leaking fuel sender assembly O-ring.
- Leaking fuel tank or fuel filler beck.

Any of the above conditions can set DTC P0440.
The test is failed if the tank vacuum is less than 2.5 kPa and the manifold vacuum integral is greater than predetermined value (proportional to purge mass from the tank) for cold test. And the test is failed if the tank vacuum is less than 10 in. H2O during PRESET mode and manifold vacuum integral is greater than 2400 cts (proportional to purge mass from the tank) for preset test.

Conditions for Setting the DTC
- DTC(s) P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0300, P0402, P0404, P0405, P0406, P0443, P0452, P0453, P0502, P0462, P0463, P0506, P0507, P1133, P1134, P1404, P1167, P1171 will not set.
1. Ignition voltage is between 11 V and 16 V.
2. Barometric Pressure (Baro) is greater than 72 kPa (10.4 psi).
3. Start-up Engine Coolant Temperature (ECT) and Intake Air Temperature (IAT) is between -5 °C (23 °F) and 40 °C (104 °F).
4. The difference between Start-up Intake Air Temperature (IAT) and IAT is less than 3 °C (5.4 °F).
5. At start-up, IAT-ECT is less than 12 °C (21.6 °F).
6. At start-up, ECT-IAT is less than 50 °C (90 °F).
7. Purge enable time is less than 360 seconds.
8. Engine run time is between 1 second and 360 seconds plus purge enable time.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The MIL will turn off after three consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm-up cycles without a fault.
- DTC(s) can be cleared by using the scan tool.

Diagnostic Aids
Although this DTC is considered a type A diagnostic, it acts like a type B diagnostic under certain conditions. Whenever this diagnostic reports the system has passed, or if the battery is disconnected, the diagnostic must fail twice before setting a DTC. The initial failure is not reported to the diagnostic executive or displayed on a scan tool. A passing system always reports to the diagnostic executive immediately. Check for the following conditions:
- Missing or damaged fuel cap.
- Missing or damaged O-rings at fuel vapor and EVAP emission purge line canister fittings.
- Cracked or punctured EVAP emission canister.
- Damaged source vacuum line, EVAP emission purge line, EVAP emission vent hose or fuel tank vapor line.
- Poor connection at ECM. Inspect harness connectors for the following conditions:
- Backed-out terminals
- Improper mating
- Broken locks
- Improperly formed
- Damaged terminals
- Poor terminal-to-wire connection

- Damaged harness. Inspect the wiring harness to the EVAP emission vent solenoid, EVAP emission canister purge valve, and the fuel tank pressure sensor for an intermittent open or short circuit.
- Kinked, pinched or plugged vacuum source, EVAP emission purge, or fuel tank vapor line. Verify that the lines are not restricted.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
4. If a vent solenoid or EVAP Canister Purge Valve electrical malfunction is present, the purge system will not operate correctly.
5. Checks the fuel tank pressure sensor at ambient pressure.
6. Determines whether or not the EVAP system is sealed sufficiently to be pressurized. If not, the large leak must be located and corrected before continuing with diagnosis.
7. Verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.
10. Ensures that sufficient source vacuum is present at the EVAP Canister Purge Valve.
11. Checks for a stuck, closed EVAP Canister Purge Valve.
18. Insures proper system integrity.

Step 1 - 18:

Step 18: