P1441
DTC P1441 Evaporative Emission (EVAP) System Flow During Non-Purge
Circuit Description
Canister purge is controlled by a solenoid valve that allows manifold vacuum to purge the canister. The powertrain control module (PCM) supplies a ground to energize the solenoid valve (purge ON). The EVAP purge solenoid control is pulse-width modulated (PWM) and is turned ON and OFF several times a second. The duty cycle (pulse width) is determined by engine operating conditions including load, throttle position, coolant temperature and ambient temperature. The duty cycle is calculated by the PCM and the output is commanded when the appropriate conditions have been met.
The EVAP purge vacuum switch is a normally closed switch positioned in the purge line between the canister and the EVAP purge solenoid. The EVAP purge vacuum switch will open when vacuum increases to greater than 5 inches of water pressure in the purge line. The PCM monitors the EVAP purge vacuum switch signal to determine if the evaporative emission control system is working properly. If the switch is open (purge flow detected) when the PCM is not commanding the EVAP purge solenoid ON, DTC P1441 will be set. DTC P1441 is a type A code.
Conditions for Setting the DTC
- No active system voltage, ECT sensor, IAT sensor, VS sensor, MAP sensor, vacuum switch, or TP sensor DTCs set.
- BARO reading is above 72.3 kPa.
- Start-up intake air temperature (IAT) and start-up engine coolant temperature (ECT) are both between 3.5 °C (38 °F) and 32 °C (90 °F).
- The difference between start-up ECT and start-up IAT is less than 6.75 °C (12.2 °F).
- The Fuel Tank Level Sensor reads between 10 % and 90 %.
- The vehicle speed is less than 98 km/h (60 mph).
- Fuel thank vacuum is greater than 15.25 cm (6 inches) of water for 0.5 seconds.
Action Taken When the DTC Sets
- The PCM will illuminate the malfunction indicator lamp (MIL) after the second consecutive trip in which the fault is detected.
- The PCM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.
Conditions for Clearing the MIL/DTC
- The PCM will turn the MIL OFF on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
- A history DTC P1441 will clear after 40 consecutive warm-up cycles have occurred without a fault.
- DTC P1441 can be cleared by using the Scan Tool's "Clear Info" function.
Diagnostic Aids
Check for the following conditions:
- Poor connection at PCM - Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.
- The Fuel Pressure Sensor shares a 5 Volt reference with the MAP sensor and TP sensor.
If these codes are also set, it could indicate a problem with the 5 Volt reference circuit or components itself.
- The Fuel Pressure Sensor share a ground with the MAP sensor and the TP sensor.
- Damaged harness - Inspect the wiring harness for damage; shorts to ground, shorts to ,battery positive, and open circuits. If the harness appears to be OK, observe the EVAP vacuum switch display on the Tech 2 while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault.
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Steps 1 - 2:
Steps 3 - 5:
Steps 6 - 7:
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart:
2. The canister purge vacuum switch is normally closed when no vacuum (purge) is present. With the ignition ON and the engine OFF, there shouldn't be any vacuum (purge) present in the EVAP system.
3. Determines if the PCM is able to control the EVAP purge solenoid valve.
4. Determines if the DTC will set under the conditions present when the DTC was originally stored. If not, the fault is intermittent.
5. Checks for a grounded EVAP purge solenoid driver circuit, a faulty EVAP vacuum switch, or a leaking EVAP purge solenoid valve.