| Table 1: | DTC P1441 |
System Description
This DTC tests for undesired intake manifold vacuum flow to the evaporative emission (EVAP) system. The control module seals the EVAP system by commanding the EVAP canister purge valve Closed and the EVAP canister vent valve Closed. The control module monitors the fuel tank pressure (FTP) sensor to determine if a vacuum is being drawn on the EVAP system. If vacuum in the EVAP system is more than a predetermined value within a predetermined time, this DTC sets.
The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent valves.
Control Module Command | EVAP Canister Purge Valve | EVAP Canister Vent Valve |
|---|---|---|
ON | Open | Closed |
OFF | Closed | Open |
Conditions for Running the DTC
| • | DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0440, P0442, P0446, P0452, or P0453 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. |
| • | 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 vehicle speed sensor (VSS) is less than 121 kmh (75 mph). |
Conditions for Setting the DTC
The control module detects vacuum during a non-purge condition.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the 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
An intermittent condition could be caused by an improperly installed or damaged EVAP canister purge valve or a temporary blockage in the EVAP canister purge valve. To repair a blockage in the EVAP system, refer to Evaporative Emission System Cleaning .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Removing the fuel fill cap will equalize the pressure inside the tank with atmospheric pressure. At 0 inches of H2O the FTP sensor should be near 1.5 volts. If the FTP is not, there is a concern with the sensor or related wiring.
-
This step checks for a leaking purge valve.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Evaporative Emissions Hose Routing Diagram | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 | Are DTCs P0452 or P0453 also set? | -- | Go to Step 3 | |
Does the scan tool indicate FTP voltage near the specified value? | 1.5 V | Go to Intermittent Conditions | Go to Step 5 | |
Does the vacuum gage indicate an increase in vacuum? | -- | Go to Step 8 | Go to Step 4 | |
5 | Does the scan tool indicate FTP voltage above the specified value? | 4.3 V | Go to DTC P0453 | Go to Step 6 |
6 | Test for poor connections at the harness connector of the FTP. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs i n Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 7 |
7 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- |
8 | Inspect the EVAP system for carbon release. Refer to Evaporative Emission System Cleaning . Did you find carbon release? | -- | Go to Step 10 | Go to Step 9 |
9 | Replace the EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- |
10 |
Does the DTC run and pass? | -- | Go to Step 11 | Go to Step 3 |
11 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTC's that you have not diagnosed? | -- | System OK | |
