Circuit Description
The evaporative system includes the following components:
| • | The fuel tank |
| • | The EVAP vent solenoid |
| • | The fuel tank pressure sensor |
| • | The fuel pipes and the hoses |
| • | The fuel vapor lines |
| • | The fuel cap |
| • | The EVAP canister |
| • | The purge lines |
| • | The EVAP canister purge valve |
| • | The EVAP service port |
The evaporative emission system is tested by applying vacuum to the EVAP system and by monitoring for a vacuum decay. The Powertrain Control Module (PCM) monitors the vacuum level through the fuel tank pressure sensor signal. At an appropriate time, the EVAP canister purge valve and the EVAP vent solenoid are turned on, allowing the engine to draw a small vacuum on the entire evaporative emission (EVAP) system. After the desired vacuum level has been achieved, the EVAP canister purge valve is turned off, sealing the system.
The EVAP canister purge valve controls the amount of engine vacuum applied to the EVAP canister. The PCM supplies a ground in order to energize the solenoid valve. The EVAP canister purge valve control is pulse width modulated (PWM) from 8 to 16 cycles per second. The duty cycle (pulse width) is determined by the engine operating conditions including the following items:
| • | The engine load |
| • | The throttle position |
| • | The engine coolant temperature |
| • | The ambient temperature |
The system tests for conditions that cause the EVAP system to purge continuously by commanding the EVAP canister purge valve off. If the fuel tank vacuum level increases during the test, a continuous purge flow condition is indicated. This can be caused by the following conditions:
| • | A leak in the EVAP canister purge valve |
| • | The following lines may be switched at the EVAP canister purge valve: |
| - | The EVAP purge |
| - | The engine vacuum |
| • | The driver circuit of the EVAP canister purge valve is grounded |
If any of these conditions are present, DTC P1441 will set.
Conditions for Running the DTC
| • | The following DTCs are not set: P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0452, P0453, P0502, P0503, P0601, P0602, P1621 and P1133. |
| • | The barometric pressure (BARO) is more than 75 kPa. |
| • | The intake air temperature (IAT) is between 5°C and 29°C (41°F- 84°F) at engine start up. |
| • | The engine coolant temperature (ECT) is between 5°C and 29°C (41°F- 84°F) at engine start up. |
| • | The IAT is not more than 1°C (2°F) above the ECT at start up. |
| • | The ECT is not more than 7°C (12°F) above the IAT at start up. |
| • | The fuel tank level is between 26 percent and 74 percent. |
| • | The TP sensor is between 7 percent and 35 percent. |
| • | The EVAP solenoid is at 40 percent PWM. |
Conditions for Setting the DTC
The EVAP system is able to detect vacuum during the diagnostic test.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information. |
| • | A history DTC stores. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn off after 3 consecutive ignition cycles in which the diagnostic runs a pass. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a malfunction. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
Although this DTC is considered a type A diagnostic, the DTC acts like a type B diagnostic under certain conditions. Whenever this diagnostic reports that the system has passed, or if the battery is disconnected, the diagnostic must fail twice before setting a DTC. The initial failure does not report to the diagnostic executive or display on a scan tool. A passing system always reports to the diagnostic executive immediately.
Inspect for the following conditions:
| • | Inspect the harness connectors for the following conditions: |
| - | Any backed out terminals |
| - | Any incorrect terminal mating |
| - | Any broken locks |
| - | Any incorrectly formed connectors |
| - | Any damaged terminals |
| - | A poor terminal to wire connection |
| • | Inspect the wiring harness for damage. If the harness appears to be OK, connect the J 41413 EVAP pressure/purge diagnostic station to the EVAP service port, pressurize the EVAP system to 10 inches of H2O, and observe the Fuel Tank Pressure display on a scan tool while moving the electrical connectors and the wiring harnesses related to the EVAP canister purge valve. A sudden change in the display will indicate the location of the malfunction. |
| • | Verify that the source vacuum line routing to the EVAP canister purge valve is correct and that the EVAP purge and the source vacuum lines to the EVAP canister purge valve are not switched. |
| • | Check for loose carbon in the purge solenoid. Blow out the lines and replace the purge canister. Refer to Evaporative Emission System Cleaning . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
If an EVAP canister purge solenoid valve electrical malfunction is present, the purge system will not operate correctly. Repairing the electrical malfunction will most likely correct the condition that set DTC P1441.
-
This step tests the fuel tank pressure sensor at ambient pressure.
-
This step verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.
-
If the EVAP purge and engine vacuum lines are switched at the EVAP canister purge solenoid valve, the solenoid valve will leak vacuum.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |||||
Does the purge valve and vent solenoid click when command on and off? | -- | Go to Step 3 | ||||||
Is the Fuel tank pressure within the specified value range? | -0.32 - +0.32 kPa (-1.28 - +1.28 in. H2O) | Go to Step 5 | Go to Step 4 | |||||
4 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage or DTC P0453 Fuel Tank Pressure Sensor Circuit High Voltage | ||||
5 |
Important:: Before continuing with the diagnosis, zero the EVAP Pressure and Vacuum gauges on the J 41413 EVAP pressure/purge diagnostic station. Also read the temperature variation and refer to the tool operating instructions.
Important: Do not exceed the pressure given in the specified value. Can the specified value be achieved? | 1.25 kPa (5 in. H2O) | Go to Step 6 | Go to Step 7 | ||||
Is the Fuel Tank pressure within the second specified value range? | 1.25 kPa (5 in. H2O) 1.25 kPa +/-0.25 kPa (5 in. H2O +/- in. H2O) | Go to Step 7 | Go to DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage or DTC P0453 Fuel Tank Pressure Sensor Circuit High Voltage | |||||
7 |
Does the EVAP canister purge valve maintain the vacuum at the specified value? | 50.81 kPa (15 in. Hg) | Go to Step 8 | Go to Step 9 | ||||
Did you find and correct the condition? | -- | Go to Step 11 | Go to Diagnostic Aids | |||||
9 |
Notice: The EVAP canister may have released carbon particles which caused this part to fail and may cause damage to other components. Check the EVAP canister for loose carbon before returning the vehicle to service. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||
10 |
Does the pressure remain equal to or more than the specified value while the EVAP Seal System is on? | 0 kPa (0 in. H2O) | Go to Step 11 | -- | ||||
11 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
