Diagnostic Aids

WARNING: This page is about a different variant/trim than selected.

The ECM uses the FTP sensor to detect the amount of vacuum pulled on the EVAP system during the leak diagnostic tests. Ensure that the fuel pressure sensor is not skewed by verifying the FTP sensor on the scan tool is between 1.30-1.70 volts with the ignition ON and the fuel cap removed.
If DTC P0455 fails, a warm test will be performed and can only pass, not fail, a diagnostic test. The purpose of this test is to keep the malfunction indicator lamp (MIL) OFF during the initial test if the customer starts the vehicle with the fuel cap off.
Visually inspect for a large leak in the EVAP system. Locate the leak with the J 41413-200 (J 41413-100) Evaporative Emissions System Tester (EEST). See Special Tools .
The following are possible causes of a large leak:
- The fuel cap is missing, is incorrectly installed or is leaking.
- The EVAP canister vent solenoid valve is stuck open.
- The EVAP canister purge solenoid valve is stuck closed or is blocked.
- The EVAP vent hose is loose or is damaged.
- The EVAP canister is leaking.
- The fuel sender assembly O-ring is leaking.
- The fuel tank or filler neck is leaking.
- A condition may exist where a leak in the EVAP system only exists under a vacuum condition. By using the scan tool Purge/Seal function to create a vacuum, seal the system and observe the fuel tank pressure (FTP) parameter for vacuum decay, this type of leak may be detected.

DTC P0455

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Evaporative Emissions (EVAP) Hose Routing Diagram Connector End View Reference: Engine Control Module (ECM) Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	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 . 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?	-	Go to Step 35	Go to Step 3
3	Clear the DTCs with a scan tool. Command the EVAP canister purge solenoid valve to 50 percent and back to 0 percent with a scan tool. Do you hear or feel a clicking from the EVAP canister purge solenoid valve when it is commanded to 50 percent?	-	Go to Step 4	Go to Step 5
4	Command the EVAP canister vent solenoid valve ON and OFF with the scan tool. Do you hear or feel a click as the EVAP canister vent solenoid valve is commanded ON and OFF?	-	Go to Step 9	Go to Step 7
5	Disconnect the EVAP canister purge solenoid valve. Turn ON the ignition, with the engine OFF. Connect a test lamp between the ignition 1 voltage circuit of the EVAP canister purge solenoid valve and a known good ground. Refer to Troubleshooting with a Test Lamp . Does the test lamp illuminate?	-	Go to Step 6	Go to Step 26
6	Connect a test lamp between the ignition 1 voltage circuit of the EVAP canister purge solenoid valve and the control circuit of the EVAP canister purge solenoid valve. Refer to Circuit Testing . Command the EVAP canister purge solenoid valve to 50 percent and then to 0 percent with a scan tool. Does the test lamp illuminate or pulsate when the EVAP canister purge solenoid valve is commanded to 50 percent and turn OFF when the EVAP canister purge solenoid valve is commanded to 0 percent?	-	Go to Step 21	Go to Step 19
7	Turn ON the ignition, with the engine OFF. Disconnect the EVAP canister vent solenoid valve. Connect a test lamp between the ignition 1 voltage circuit of the EVAP canister vent solenoid valve and a known good ground. Refer to Troubleshooting with a Test Lamp . Does the test lamp illuminate?	-	Go to Step 8	Go to Step 27
8	Connect a test lamp between the ignition 1 voltage circuit of the EVAP canister vent solenoid valve and the control circuit of the EVAP canister vent solenoid valve. Refer to Troubleshooting with a Test Lamp . Command the EVAP canister vent solenoid valve ON, with a scan tool. Does the test lamp illuminate?	-	Go to Step 22	Go to Step 20
9	IMPORTANT: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize. Turn the nitrogen/smoke valve to NITROGEN. Connect the nitrogen/smoke hose to the 0.5 mm (0.20 in) test orifice on the bottom-front of the J 41413-200 (J 41413-100) Evaporative Emissions System Tester (EEST). See Special Tools . Use the remote switch to activate the J 41413-200 (J 41413-100). See Special Tools . Align the red flag on the flow meter with the floating indicator. Use the remote switch to de-activate the J 41413-200 (J 41413-100). See Special Tools . Remove the nitrogen/smoke hose from the test orifice and install the hose onto one of the following sources: Connect the GE-41415-50 Fuel Tank Cap Adapter to the fuel fill pipe, and the nitrogen/smoke hose to the fuel cap adapter. See Special Tools . Connect the nitrogen/smoke hose to the EVAP service port. Turn ON the ignition, with the engine OFF. Command the EVAP canister vent solenoid valve closed with a scan tool. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating stabilizes. Compare the flow meters stable floating indicator position to the red flag. Is the floating indicator below the red flag?	-	Go to Step 12	Go to Step 10
10	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. Turn ON the ignition, with the engine OFF. Command the EVAP canister vent solenoid valve closed with a scan tool. Turn the nitrogen/smoke valve on the J 41413-200 (J 41413-100) control panel to SMOKE. See Special Tools . Use the remote switch to introduce smoke into the EVAP system. Use the J 41413-VLV EVAP Service Port Vent Fitting to open the EVAP service port. See Special Tools . Remove the J 41413-VLV once smoke is observed. See Special Tools . Continue to introduce smoke into the EVAP system for an additional 60 seconds. Inspect the entire EVAP system for exiting smoke with a High Intensity White Light. Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source?	-	Go to Step 35	Go to Step 11
11	Disconnect the GE-41415-50 from the fuel fill pipe. See Special Tools . Install the fuel fill cap to the fuel fill pipe. Connect the J 41413-200 (J 41413-100) nitrogen/smoke supply hose to the EVAP service port. See Special Tools . Use the remote switch to introduce smoke into the EVAP system. Inspect the entire EVAP system for exiting smoke with a High Intensity White Light. Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source?	-	Go to Step 35	Go to Step 12
12	Use the remote switch to stop introducing smoke. Install the nitrogen/smoke supply hose onto one of the following sources: Connect GE-41415-50 to the fuel fill pipe, and the nitrogen/smoke hose to the fuel cap adapter. See Special Tools . Connect the nitrogen/smoke hose to the EVAP service port. Connect the vehicle fuel fill cap to the GE-41415-50 . See Special Tools . Command the EVAP canister vent solenoid valve open with a scan tool. Observe the Fuel Tank Pressure Sensor parameter with a scan tool. Is the scan tool Fuel Tank Pressure Sensor parameter within the specified value?	1.30-1.70 V	Go to Step 13	Go to Step 23
13	Seal the EVAP system using the EVAP Purge/Seal function with a scan tool. Turn the nitrogen/smoke valve on the J 41413-200 (J 41413-100) control panel to NITROGEN. See Special Tools . Use the J 41413-200 (J 41413-100) to pressurize the EVAP system to the first specified value. See Special Tools . Is the Fuel Tank Pressure Sensor parameter less than the second specified value?	10 in H2O 0.5 V	Go to Step 14	Go to Step 23
14	Use the remote switch to stop introducing nitrogen into the EVAP system. Increase the EVAP canister purge solenoid valve to 100 percent. Is the Fuel Tank Pressure Sensor parameter within the specified value?	1.30-1.70 V	Go to Diagnostic Aids	Go to Step 15
15	Disconnect the EVAP purge vacuum source from the EVAP canister purge solenoid valve. Is the Fuel Tank Pressure Sensor parameter within the specified value?	1.30-1.70 V	Go to Step 25	Go to Step 16
16	Disconnect the EVAP purge pipe from the EVAP canister purge solenoid valve. Is the Fuel Tank Pressure Sensor parameter within the specified value?	1.30-1.70 V	Go to Step 30	Go to Step 17
17	Disconnect the EVAP purge pipe at the EVAP canister. Is the Fuel Tank Pressure Sensor parameter within the specified value?	1.30-1.70 V	Go to Step 28	Go to Step 18
18	Disconnect the EVAP vapor pipe at the EVAP canister. Is the Fuel Tank Pressure Sensor parameter within the specified value?	1.30-1.70 V	Go to Step 32	Go to Step 29
19	Test the control circuit of the EVAP canister purge solenoid valve for an open or for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 35	Go to Step 24
20	Test the control circuit of the EVAP canister vent solenoid valve for an open or for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 35	Go to Step 24
21	Test for an intermittent and for a poor connection at the EVAP canister purge solenoid valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 35	Go to Step 30
22	Test for an intermittent and for a poor connection at the EVAP canister vent solenoid valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 35	Go to Step 31
23	Test for an intermittent and for a poor connection at the fuel tank pressure (FTP) sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 35	Go to Step 33
24	Test for an intermittent and for a poor connection at the control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 35	Go to Step 34
25	Repair the pinched or obstructed EVAP canister purge solenoid valve vacuum source. Did you complete the repair?	-	Go to Step 35	-
26	Repair the open or short to ground in the ignition 1 voltage circuit of the EVAP canister purge solenoid valve. Refer to Wiring Repairs . Replace the fuse as necessary. Did you complete the repair?	-	Go to Step 35	-
27	Repair the open or short to ground in the ignition 1 voltage circuit of the EVAP canister vent solenoid valve. Refer to Wiring Repairs . Replace the fuse as necessary. Did you complete the repair?	-	Go to Step 35	-
28	Repair the restriction in the EVAP purge pipe. Did you complete the repair?	-	Go to Step 35	-
29	Repair the restriction in the EVAP vapor pipe. Did you complete the repair?	-	Go to Step 35	-
30	Replace the EVAP canister purge solenoid valve. Refer to Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement . Did you complete the replacement?	-	Go to Step 35	-
31	Replace the EVAP canister vent solenoid valve. Refer to Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement . Did you complete the replacement?	-	Go to Step 35	-
32	Replace the EVAP canister. Refer to Evaporative Emission (EVAP) Canister Replacement . Did you complete the replacement?	-	Go to Step 35	-
33	Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement?	-	Go to Step 35	-
34	Replace the engine control module (ECM). Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	-	Go to Step 35	-
35	IMPORTANT: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize. Turn the nitrogen/smoke valve to NITROGEN. Connect the nitrogen/smoke hose to the 0.5 mm (0.20 in) test orifice on the bottom-front of the J 41413-200 (J 41413-100). See Special Tools . Use the remote switch to activate the J 41413-200 (J 41413-100). See Special Tools . Align the red flag on the flow meter with the floating indicator. Use the remote switch to de-activate the J 41413-200 (J 41413-100). See Special Tools . Remove the nitrogen/smoke hose from the test orifice and install the hose onto one of the following sources: Connect the GE-41415-50 to the fuel fill pipe, and the nitrogen/smoke hose to the fuel cap adapter. See Special Tools . Connect the nitrogen/smoke hose to the EVAP service port. Turn ON the ignition, with the engine OFF. Command the EVAP canister vent solenoid valve closed with a scan tool. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating stabilizes. Compare the flow meters stable floating indicator position to the red flag. Is the floating indicator below the red flag?	-	Go to Step 36	Go to Step 2
36	Seal the EVAP system using the EVAP Purge/Seal function with a scan tool. Turn the nitrogen/smoke valve on the J 41413-200 (J 41413-100) control panel to NITROGEN. See Special Tools . Use the J 41413-200 (J 41413-100) to pressurize the EVAP system to the first specified value. See Special Tools . Is the Fuel Tank Pressure Sensor parameter less than the second specified value?	10 in H2O 0.5 V	Go to Step 37	Go to Step 2
37	Use the remote switch to stop introducing nitrogen into the EVAP system. Increase the EVAP canister purge solenoid valve to 100 percent. Is the Fuel Tank Pressure Sensor parameter within the specified value?	1.30-1.70 V	Go to Step 38	Go to Step 2
38	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	System OK