DTC P0455. GMC Truck Envoy

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2005 🢒 Envoy - 4WD 🢒 Engine 🢒 Engine Controls - 4.2L 🢒 DTC P0455

System Description

The control module tests the Evaporative Emission (EVAP) System for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge solenoid valve OPEN and the EVAP vent solenoid valve CLOSED . This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge solenoid valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and vent solenoid valves.

Control Module Command	EVAP Canister Purge Solenoid Valve	EVAP Canister Vent Solenoid Valve
ON	Open	Closed
OFF	Closed	Open

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0455 Evaporative Emissions (EVAP) System Large Leak

Conditions for Running the DTC

•	DTCs P0068, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0220, P0452, P0453, P0502, P0503, P0601, P0602, P0604, P0606, P060D, P060E, P0641, P1133, P1516, P1621, P2101, P2120, P2125, P2135, P2138, P2176 are not set.

•	The engine is running.

•	The EVAP canister purge solenoid valve is enabled.

•	The ignition voltage is between 11-18 volts.

•	The throttle position (TP) is between 7-35 percent.

•	The barometric pressure (BARO) is more than 74 kPa.

•	The fuel level is between 15-85 percent.

•	The start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F).

•	The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).

•	The start-up ECT and IAT are within 8°C (14.4°F) of each other.

•	The vehicle speed sensor (VSS) is less than 137 km/h (85 mph).

•	DTC P0455 runs once per trip when the above conditions are met.

Conditions For Setting the DTC

The EVAP system is not able to achieve or maintain vacuum of 10 inches H2O for 30 seconds during the diagnostic 5.5-minute test.

Action Taken When the DTC Sets

•	The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

•

The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

•	The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

•	A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

•	A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

•	Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

•	A loose, incorrect, missing, or damaged fuel cap can cause this DTC to set.

•	To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light.

•	A temporary blockage in the EVAP canister purge solenoid valve, purge pipe or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.

•	To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .

•	Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

•	For intermittent conditions refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

This test verifies that the EVAP canister purge solenoid valve is electrically functional.

This test verifies that the EVAP canister vent solenoid valve is electrically functional.

Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.

This test verifies that the FTP sensor is accurate. An FTP sensor that does not correctly respond to vacuum, or pressure may cause this DTC to set.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics or Evaporative Emissions Hose Routing Diagram

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

Inspect the evaporative emission (EVAP) system for the following conditions:

•	A loose, missing, or damaged service port schrader valve

•	A loose, incorrect, missing, or damaged fuel fill cap

•	A damaged EVAP canister purge solenoid valve

Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle in General Information.
Inspect the EVAP system for the following conditions:

•	Any disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses

•	A damaged EVAP canister vent solenoid valve or EVAP canister

Did you find and correct the condition?