Circuit Description
The PCM tests the 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 sensor in order to determine the level of vacuum/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 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. The EVAP system should HOLD the vacuum in the sealed system. The PCM sets this DTC in order to indicate a small leak if the EVAP system fails to hold a predetermined level of vacuum for a predetermined length of time. This DTC sets after failing the above test twice.
Conditions for Running the DTC
| • | DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0420, P0430, P0500, P0502, P0503, P0562, P0563, P1120, P1220, P1221, and HO2S DTCs are not set. |
| • | The barometric pressure is greater than 75 kPa. |
| • | The fuel level is between 15% and 85% of full capacity. |
| • | The engine coolant temperature is between 4°C (39°F) and 30°C (86°F). |
| • | The intake air temperature is between 4°C (39°F) and 30°C (86°F). |
| • | The start up engine coolant temperature and intake air temperature are within 9°C (16°F) of each other. |
| • | The throttle position angle is less than 75% during the weak vacuum test. |
| • | The vehicle speed is less than 113 km/h (70 mph) during the weak vacuum test. |
Conditions for Setting the DTC
The vacuum in the EVAP system decays (leaks) at too fast a rate.
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 to determine if this DTC has failed or passed for this ignition cycle.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL and the DTC. |
Diagnostic Aids
Important:
• Remove any debris from the PCM\TAC module connector surfaces before
servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets
when diagnosing/replacing the modules. Ensure that the gaskets are
installed correctly. The gaskets prevent contaminate intrusion into
the PCM\TAC modules. • For any test that requires probing the PCM or a component
harness connector, use the Connector Test Adapter Kit J 35616
. Using this kit prevents damage to the harness/component
terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | An accurate indication of fuel level is required for the PCM to properly Pass or Fail this DTC. Always diagnose fuel level sensor DTC's before performing this diagnostic table. Always monitor 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. |
| • | 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 |
| • | 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 H2O (water). Most gauges measure vacuum in inches of Hg (mercury) and pressure in psi (pounds per square inch). The following table illustrates 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. |
Conditions for Running the Service Bay Test
| • | The battery voltage is between 10.5 and 18.0 volts. |
| • | The fuel level is between 15% and 85% of the full capacity. |
| • | The engine temperature is between 3.5°C (38°F) and 35°C (95°F). |
| • | Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This isolates when the DTC failed. |
| • | For an intermittent, refer to Symptoms . |
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
-
It may be necessary to partially lower the fuel tank to inspect the upper portion of the tank and the EVAP line connections.
-
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.
-
Refer to the information supplied with the EVAP pressure/purge diagnostic cart on proper setup and adjustment procedures.
-
An Fuel Tank Pressure sensor that does not correctly respond to pressure or vacuum will cause this DTC to set.
The Fuel Tank Pressure sensor range is from 7.5 in. H2O of pressure to -17.5 in. H2O of pressure (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 | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
2 | Are any other EVAP system DTCs set? | -- | Go to applicable DTC | |||||||
Inspect the EVAP system for the following conditions:
Repair as necessary if you find a problem. 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 | ||||||||
5 |
Can the value specified be obtained and held? | 12 in. Hg. | ||||||||
6 |
Can the specified value be obtained and held? | 5 in. Hg. | ||||||||
7 |
Can the specified value be obtained and held? | 5 in. Hg. | ||||||||
8 |
Was the EVAP Vent line replaced? | -- | ||||||||
|
Important: The following steps require the EVAP pressure/purge diagnostic station J 41413 and J 41416 the ultrasonic leak detector. Always zero the EVAP Pressure and Vacuum (in. H2O) gauges on the EVAP pressure/purge diagnostic station before proceeding with diagnosis. Refer to the users guide.
Did you find and correct the condition? | -- | |||||||||
10 |
Important: Inspect the EVAP Purge Solenoid Valve and the purge line for carbon contamination. Refer to Diagnostic Aids. Replace the EVAP Purge Solenoid Valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Is the replacement complete? | -- | -- | |||||||
11 | Replace the EVAP Vent Valve. Refer to Evaporative Emission Vent Valve Replacement . Is the replacement complete? | -- | -- | |||||||
12 | Replace the EVAP Vapor Canister. Refer to Evaporative Emission Canister Replacement . Is the replacement complete? | -- | -- | |||||||
Does the Fuel Tank Pressure sensor indicate the actual amount of pressure in the EVAP system? | -- | Go to Step 3 | ||||||||
14 | Replace the Fuel Tank Pressure sensor. Refer to Fuel Tank Pressure Sensor Replacement . Is the action complete? | -- | -- | |||||||
15 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||||
16 | 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 Applicable DTC | System OK |
