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 and then monitors the vacuum decay rate. The PCM sets this diagnositc trouble code (DTC) if the vacuum decay rate is more than a predetermined value.
Conditions for Running the DTC
| • | DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0420, P0430, P0452, P0453, P0500, P0562, P0563, or heated oxygen sensor (HO2S) DTCs are not set. |
| • | The ignition voltage is between 10 and 17 volts. |
| • | The barometric pressure is more than 75 kPa. |
| • | The fuel level is between 15 and 85 percent of full capacity. |
| • | The engine coolant temperature (ECT) is between 4°C (39°F) and 30°C (86°F). |
| • | The intake air temperature (IAT) is between 4°C (39°F) and 30°C (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 when the vent solenoid is commanded open. |
| • | The conditions are present for more than 2 seconds. |
OR
| • | The vacuum present in the EVAP system is more than a predetermined value when the vent solenoid is commanded open during normal purge. |
| • | The conditions are present for more than 4 seconds. |
Action Taken When the DTC Sets
| • | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
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 contaminate intrusion into the PCM. • For any test that requires probing the PCM or a component
harness connector, use the J 35616
connector test adapter kit. Using this kit prevents damage
to the harness and component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | A fuel tank pressure sensor ground circuit that is open will cause this DTC to set. The fuel tank pressure sensor and the fuel level sensor share the same ground. IF DTC P0463 is also set, inspect the common ground for an open. |
| • | 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 performing this DTC table. Always inspect for fuel level sensor DTCs stored as History. |
| • | 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 stuck closed EVAP vent valve |
| - | A restricted or blocked EVAP system hose |
| - | A restricted or stuck closed fuel tank rollover valves |
| - | A malfunctioning or damaged vapor canister |
| • | Inspect for charcoal release from the vapor canister. Refer to the Evaporative Emission System Cleaning procedure. |
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 |
|---|---|---|
1 in. 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 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. |
Conditions for Running the Service Bay Test
| - | The battery voltage is between 10.5 and 17.5 volts. |
| - | The fuel level is between 15 percent and 85 percent of the full capacity. |
| - | The engine temperature is between 3.5°C (38°F) and 35°C (95°F). |
| • | The scan tool displays Test Aborted if any of the above conditions are not met. |
| • | For an intermittent, refer to Symptoms . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
An intermittent leak or restriction is indicated if the vehicle passes the Service Bay Test. A fuel tank cap that is loose or off causes this DTC to set.
If the Service Bay Test can not be run, proceed to step 5. If a fault is not currently present the diagnostic table steps will return you to step 3.
-
This step is testing the vapor canister and the EVAP vent valve for restriction.
-
A fuel tank pressure sensor that does not correctly respond to pressure or vacuum causes this DTC to set. An open fuel tank pressure sensor ground circuit will cause this DTC to set. If the fuel tank pressure sensor does not respond to pressure or vacuum inspect the ground circuit for an open.
The fuel tank pressure sensor range is from +7.5 in. H2O of pressure to -17.5 in. H2O of pressure or vacuum.
In order to test the fuel tank pressure sensor for vacuum response, command the EVAP purge solenoid valve ON with the engine running and quickly SEAL the system. Leaving the EVAP purge solenoid valve ON for a longer period of time allows a greater level of vacuum to develop.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||
2 |
Did you find and correct the condition? | -- | ||||||
|
Important: Ensure that the Conditions for Running the Service Bay Test are met before proceeding with this diagnostic. Refer to Diagnostic Aids. Perform the EVAP system Service Bay Test. Does the vehicle pass the Service Bay Test? | -- | Go to Diagnostic Aids | ||||||
Does the vacuum drop from the specified value when the EVAP vent valve is opened? | 5 in. Hg | |||||||
5 |
Does the vacuum drop from the specified value when the vent line is unplugged? | 5 in. Hg | ||||||
6 |
Did you find and correct the condition? | -- | ||||||
7 |
Did you find and correct the condition? | -- | ||||||
|
Important: The following steps require the J 41413 EVAP pressure/purge diagnostic station. Always zero the EVAP pressure and vacuum (in. H2O) gauges on the J 41413 EVAP pressure/purge diagnostic station before proceeding with diagnosis. Refer to the users guide.
Important: Refer to test description for further information. Does the fuel tank pressure sensor indicate the actual amount of vacuum in the EVAP system? | -- | |||||||
9 | Replace the EVAP vent valve. Refer to Evaporative Emission Vent Valve Replacement . Is the action complete? | -- | -- | |||||
10 | Replace the EVAP vapor canister. Refer to Evaporative Emission Canister Replacement . Is the action complete? | -- | -- | |||||
11 | Replace the fuel tank pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement . Is the action complete? | -- | -- | |||||
12 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||
13 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
