Circuit Description
The powertrain control module (PCM) monitors the performance of the evaporative emission (EVAP) system by applying a predetermined level of vacuum to the EVAP system then monitors the vacuum decay rate. The PCM sets this diagnostic trouble code (DTC) if the vacuum decay rate is more than a predetermined value.
Conditions for Running the DTC
| • | DTCs P0107, P0108, P0110, P0112, P0113, P0115, P0117, P0118, P0121, P0121, P0122, P0123, P0125, P0440, P0442, 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 (BARO) is more than 75 kPa. |
| • | The fuel level is between 15-85 percent of full capacity. |
| • | The engine coolant temperature (ECT) is between 4-30C (39-86°F). |
| • | The intake air temperature (IAT) is between 4-30C (39-86°F). |
| • | The start up ECT and the IAT are within 9°C (16°F) of each other. |
Conditions for Setting the DTC
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.
| • | The EVAP vacuum decay rate is more than a predetermined value. |
| • | The conditions are present for more than 2 seconds. |
OR
| • | The vacuum present in the EVAP system is more than a predetermined value. |
| • | The conditions are present for more than 4 seconds. |
Action Taken When the DTC Sets
| • | 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. |
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
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 the fuel level sensor DTCs
before using the diagnostic table for this DTC. Always
inspect for fuel level sensor DTCs that are 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 a charcoal release from the vapor canister. Refer
to
Evaporative Emission System Cleaning
procedure.
Conditions for Running the Service Bay Test
| • | 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 |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | 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 | Did DTC P0443, P0449, P0452, or P0453 set? | -- | Go to Step 3 | |||||
3 | Inspect the EVAP system for the following conditions:
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 4 | ||||
Does the scan tool indicate that the Service Bay Test has passed? | -- | Go to Diagnostic Aids | Go to Step 5 | |||||
5 |
Does the scan tool indicate fuel tank pressure near the specified value? | 0 in H2O | Go to Step 6 | Go to Step 10 | ||||
6 |
Does the scan tool indicate fuel tank pressure (FTP) near the second specified value? | 5 in H2O 0 in H2O | Go to Step 8 | Go to Step 7 | ||||
7 |
Does the scan tool indicate fuel tank pressure near the second specified value? | 5 in H2O 0 in H2O | Go to Step 11 | Go to Step 9 | ||||
8 | Replace the EVAP vent valve. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
9 | Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
10 | Replace the fuel tank pressure (FTP) sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
11 | Repair for a blockage in the EVAP vent hose. Did you complete the repair? | -- | Go to Step 12 | -- | ||||
12 |
Does the scan tool indicate that the Service Bay Test has passed? | -- | Go to Step 13 | Go to Step 3 | ||||
13 | With a scan tool, select the Review Info option. Does the scan tool indicate any DTCs that have not been diagnosed? | -- | System OK | |||||
