Circuit Description
The powertrain control module (PCM) monitors the amount of vacuum or pressure in the evaporative emission (EVAP) system by monitoring the fuel tank pressure sensor signal. The PCM seals the EVAP system by commanding the EVAP purge solenoid OFF and the EVAP vent valve ON. The PCM monitors the fuel tank pressure sensor in order to determine if the EVAP purge solenoid is leaking vacuum to the EVAP system. This diagnostic trouble code (DTC) sets if the vacuum in the EVAP system is more than a predetermined value within a predetermined time.
Conditions for Running the DTC
| • | DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0420, P0430, P0500, P0563 and heated oxygen sensor (HO2S) DTCs are not set. |
| • | The ignition voltage is between 10.0 volts and 17.0 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 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 and intake air temperatures are within 9°C (16°F) of each other. |
| • | The throttle position (TP) sensor angle is less than 75 percent during the weak vacuum test. |
| • | The vehicle speed is less than 90 mph during the weak vacuum test. |
Conditions for Setting the DTC
The EVAP system develops a vacuum more than a predetermined value when purge is not commanded.
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
Before replacing any components, visually and physically inspect for the following:
| • | Mis-routed harness |
| • | Rubbed through wire insulation |
| • | Broken wire inside the insulation |
| • | Kinked or damaged vacuum hoses |
| • | Physically damaged system components |
| • | Inspect components and vacuum lines for traces of carbon or other contaminants. The presence of foreign material may be causing a restriction in the system or preventing the solenoid valve from closing properly. Either condition may cause a DTC to set. |
For an intermittent condition, refer to Symptoms .
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Does the vacuum gauge indicate a vacuum? | -- | Go to Diagnostic Aids | ||
3 |
Important: Inspect for carbon contamination. Refer to Evaporative Emission System Cleaning . Replace the EVAP purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Replacement . Is the action complete? | -- | -- | |
4 |
Does the scan tool indicate that this test ran and passed? | -- | ||
5 | 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 |
