The powertrain control module (PCM) tests the evaporative emission (EVAP) system for the following conditions:
• | Large and small leaks |
• | Excess vacuum |
• | Purge flow during non-commanded conditions |
• | Fuel level and fuel pressure sensor faults |
• | EVAP purge and vent valve faults |
The PCM monitors the fuel tank pressure (FTP) sensor in order to determine the level of vacuum or pressure in the EVAP system. The PCM commands both the EVAP purge solenoid and the EVAP vent valve ON when the Conditions for Running the diagnostic trouble code (DTC) are met in order to apply an engine vacuum to the EVAP system. The PCM commands the EVAP purge solenoid OFF once the system has reached a predetermined level of vacuum. This test confirms if a vacuum can be achieved in the EVAP system. Failure to develop a vacuum may be caused by a large leak or a restriction. This DTC sets after twice failing the above test.
• | DTCs P0107, P0108, P0110, P0112, P0113, P0115, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1106, P1107, P1111, P1112, P1114, P1115, P1121, or P1122 are not set. |
• | The ignition voltage is between 10-18 volts. |
• | The barometric pressure is more than 75 kPa. |
• | The fuel level is between 15-85 percent of full capacity. |
• | The engine coolant temperature (ECT) is between 4-30°C (39-86°F). |
• | The intake air temperature (IAT) is between 4-30°C (39-86°F). |
• | The start up ECT and IAT are within 9°C (16°F) of each other. |
The EVAP system cannot develop a vacuum more than a predetermined value.
Important: This DTC does NOT report a first failed test. A first fail of this DTC will have a scan tool status as Not Run. Use the scan tool data display parameter of EVAP test result in order to determine if this DTC has failed or passed for this ignition cycle.
• | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
• | 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. |
Important:
• Remove any debris from the PCM connector surfaces before servicing
the PCM. Inspect the PCM connector gaskets when diagnosing or replacing
the PCM. Ensure that the gaskets are installed correctly.
The gaskets prevent water intrusion into the PCM. • An accurate indication of fuel level is required for the PCM to
properly pass or fail this DTC. Always diagnose fuel level sensor DTCs
before performing this DTCs diagnostic table. Always
inspect for fuel level sensor DTCs stored as History. • The Service Bay Test may have to be performed in cold ambient
air temperatures when the vehicle is running a winter grade fuel. The scan
tool displays a message when the Service Bay Test
does not run. • Inspect for charcoal release from the vapor canister. Refer to
Evaporative Emission System Cleaning
.
• | The battery voltage is between 10.5-17.5 volts. |
• | The fuel level is between 15-85 percent of the full capacity. |
• | The engine temperature is between 3.5-35°C (38-95°F). |
Perform a physical inspection of the EVAP system. Inspect for the following conditions:
• | A loose, missing, defective, or incorrect fuel tank cap |
• | Incorrectly routed or defective EVAP system vacuum and vapor lines |
• | A malfunctioning or damaged vapor canister |
• | Charcoal release from the vapor canister--Refer to Evaporative Emission System Cleaning . |
The vacuum and pressure in the EVAP system is measured in inches of water (H2O). Most gauges measure vacuum in inches of mercury (Hg) and pressure in pounds per square inch (psi). The following shows how the values compare:
in H2O | in Hg | psi |
---|---|---|
1in H2O | 0.07 in Hg | 0.0361 psi |
5 in H2O | 0.36 in Hg | 0.180 psi |
10 in H2O | 0.73 in Hg | 0.361 psi |
15 in H2O | 1.10 in Hg | 0.541 psi |
The numbers below refer to the step numbers on the diagnostic table.
This step verifies that a failure condition is active.
This step is used to verify if a leak is present.
This step verifies proper operation of the fuel tank pressure (FTP) sensor.
This step tests the EVAP canister purge valve for a restriction or blockage.
This step verifies that repairs are complete and that no other condition is present.
Step | Action | Values | Yes | No | ||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Emission Hose Routing Diagram and Engine Controls Schematics | ||||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||||||||||
2 | Does the scan tool indicate DTC P0443 or DTC P0449 are also set? | -- | Go to Step 3 | |||||||||||||||||||||
3 |
Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 4 | ||||||||||||||||||||
Does the scan tool indicate that the service bay test passed? | -- | Go to Diagnostic Aids | Go to Step 5 | |||||||||||||||||||||
Important: The following steps require the J 41413 EVAP Pressure/Purge Diagnostic Station and the J 41415 Fuel Fill Cap Adaptor . Always zero the EVAP pressure and vacuum (in H2O) gauges on the EVAP pressure diagnostic station before proceeding with diagnosis.
Did you obtain the specified value? | 5 in H2O | Go to Step 6 | Go to Step 8 | |||||||||||||||||||||
Compare the EVAP pressure/purge diagnostic station value to the scan tool (FTP) fuel tank pressure sensor value. Does EVAP pressure/purge diagnostic station value measure near the scan tool value? | -- | Go to Step 7 | Go to Step 14 | |||||||||||||||||||||
7 |
Does the EVAP system pressure decrease? | 5 in H2O | Go to Step 10 | Go to Step 11 | ||||||||||||||||||||
8 |
Important: It may be necessary to partially lower the fuel tank to inspect components located in the upper portion of the tank.
Did you locate a leak? | -- | Go to Step 9 | Go to Diagnostic Aids | ||||||||||||||||||||
9 | Repair the system as necessary. Did you complete the repair? | -- | Go to Step 19 | -- | ||||||||||||||||||||
Does the EVAP pressure/purge diagnostic station vacuum gauge measure above the specified value? | 12 in Hg | Go to Diagnostic Aids | Go to Step 16 | |||||||||||||||||||||
11 |
Does the EVAP system pressure decrease? | -- | Go to Step 17 | Go to Step 12 | ||||||||||||||||||||
12 |
Does the EVAP system pressure decrease? | -- | Go to Step 13 | |||||||||||||||||||||
13 |
Does the EVAP system pressure decrease? | -- | Go to Step 18 | Go to Step 15 | ||||||||||||||||||||
14 | Replace the fuel tank pressure (FTP) sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- | ||||||||||||||||||||
15 | Repair for a pinched or obstructed EVAP vapor pipe between the front and rear tanks. Did you complete the repair? | -- | Go to Step 19 | -- | ||||||||||||||||||||
16 | Repair for a plugged vacuum supply. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 17 | ||||||||||||||||||||
17 | Replace the EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- | ||||||||||||||||||||
18 | Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- | ||||||||||||||||||||
Perform the Service Bay Test. Refer to Service Bay Test . Does the scan tool indicate that the service bay test passed? | -- | Go to Step 20 | Go to Step 2 | |||||||||||||||||||||
20 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |