Hummer H2. Manual - part 1664

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 canister 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.

Poor connections

Broken wires inside the insulation -
Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

Inspect for poor connections at the harness connector
of the control module. Refer to Testing for
Intermittent Conditions and Poor Connections
and Connector Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 13

Go to Step 12

Replace the FTP sensor. Refer to Fuel Tank
Pressure Sensor Replacement .
Did you complete the replacement?

Go to Step 13

Replace the control module. Refer to Powertrain
Control Module (PCM) Replacement .
Did you complete the replacement?

Go to Step 13

1. Observe the Freeze Frame/Failure Records for

this DTC.

2. Turn OFF the ignition for 30 seconds.

3. Turn ON the ignition, with the engine OFF.

4. Operate the vehicle within the Conditions for

Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/Failure
Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 14

Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?

Go to

Diagnostic

Trouble Code

(DTC) List

System OK

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0171/P0174 To DTC P0507 (TAC)) - 4.8L, 5.3L, and

6.0L - Hummer H2

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.

DTC P0455

Conditions for Running the DTC

DTC P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0125, P0131, P0132, P0133,
P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0156,
P0157, P0158, P0160, P0161, P0220, P0442, P0443, P0449, P0452, P0453, P1111, P1112, P1114,
P1115, P1125, P2135 are not set.

The engine is running.

The ignition voltage is between 10-18 volts.

The barometric pressure (BARO) is more than 75 kPa.

The fuel level is between 15-85 percent.

The engine coolant temperature (ECT) is between 4-65°C (39-149°F).

The intake air temperature (IAT) is between 4-75°C (39-167°F).

The start-up ECT and IAT are within 9°C (16°F) of each other.

Conditions For Setting the DTC

The EVAP system is not able to achieve or maintain vacuum during the diagnostic 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.

Control Module

Command

EVAP Canister Purge Solenoid

Valve

EVAP Canister Vent Solenoid

Valve

Open

Closed

OFF

Closed

Open

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0171/P0174 To DTC P0507 (TAC)) - 4.8L, 5.3L, and

6.0L - Hummer H2

Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

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. Introducing smoke in 15 second intervals will allow less pressure
into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more
condensed manner.

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.

3: 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.

5: This step verifies proper operation of the fuel tank pressure (FTP) sensor.

6: A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6 inches of
H2O and 7 inches of H2O.

DTC P0455

Step

Action

Values

Yes

Schematic Reference: Emission Hose Routing Diagram

Did you perform the Diagnostic System Check - Engine
Controls?

Go to Step 2

Go to

Diagnostic

System

Check -

Engine

Controls

1. Inspect the evaporative emission (EVAP) system

for the following conditions:

Loose, missing, or damaged service port
schrader valve

Loose, incorrect, missing, or damaged fuel
fill cap

A damaged EVAP canister purge solenoid

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0171/P0174 To DTC P0507 (TAC)) - 4.8L, 5.3L, and

6.0L - Hummer H2

valve

2. Raise the vehicle on a hoist. Refer to Lifting and

Jacking the Vehicle in General Information.

3. Inspect the EVAP system for the following

conditions:

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?

Go to Step

Go to Step 3

1. Turn OFF the ignition.

2. Connect the J 41413-200 Evaporative Emissions

System Tester (EEST) power supply clips to a
known good 12-volt source.

3. Install the GE-41415-50 Fuel Tank Cap Adapter

to the fuel fill pipe.

4. Connect the J 41413-200 nitrogen/smoke supply

hose to the GE-41415-50 .

5. Turn ON the ignition, with the engine OFF.

6. Command the EVAP canister vent solenoid valve

closed with a scan tool.

7. Turn the nitrogen/smoke valve on the J 41413-

200 control panel to SMOKE.

8. Use the remote switch to introduce smoke into

the EVAP system.

9. Use the J 41413-VLV EVAP Service Port Vent

Fitting to open the EVAP service port.

10. Remove the J 41413-VLV once smoke is

observed.

11. Continue to introduce smoke into the EVAP

system for an additional 60 seconds.

12. Inspect the entire EVAP system for exiting

smoke with the J 41413-SPT High Intensity
White Light.

13. Continue to introduce smoke at 15 second

IMPORTANT:

Ensure that the vehicle underbody temperature is
similar to the ambient temperature and allow the
surrounding air to stabilize before starting the
diagnostic procedure. System flow will be less with
higher temperatures.

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0171/P0174 To DTC P0507 (TAC)) - 4.8L, 5.3L, and

6.0L - Hummer H2

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