P1441

DTC P1441 Evaporative Emissions (EVAP) System Continuous Open Purge Flow:

Evaporative Emissions Control (EVAP) System:

CIRCUIT DESCRIPTION
Canister purge is controlled by a solenoid valve that allows ported vacuum to purge the canister when energized. The Vehicle Control Module-A (VCM-A) supplies a ground to energize the solenoid valve (purge "ON"). The purge solenoid control by the VCM-A is Pulse Width Modulated (PWM) or turned "ON" and "OFF" several times a second. The duty cycle (pulse width) is determined by "Closed Loop" feed back from the Heated Oxygen Sensor (HO2S). The duty cycle is calculated by the VCM-A and the output is commanded when certain conditions have been met. DTC P1441 is a type "B" DTC.

A vacuum switch in the purge line is used to detect when the system is being purged. The normally closed switch will open when less than .3 kPa (1 Hg) or more is present in the purge line. The VCM-A supplies a 5 volt reference to the switch to monitor if the evaporative emission control system is working properly. If the switch is open (purge detected) when the VCM-A is not commanding purge, a DTC will be set.

DTC P1441 WILL SET WHEN
^ Evaporative Emissions (EVAP) System vacuum switch state is high (open) vacuum for a period greater than 4 seconds.
^ Purge solenoid diagnostic vacuum switch DTC not set.
^ No Idle Air Control (IAC) DTCs set.
^ No Manifold Absolute Pressure (MAP) DTCs set.
^ No Throttle Position (TP) sensor DTCs set.
^ No Exhaust Gas Recirculation (EGR) DTCs set.
^ Barometric Absolute Pressure (BARO) greater than 75 kPa (23 Hg).
^ Engine Coolant Temperature (ECT) is no more than 110°C (230°F).
^ Power up Intake Air Temperature (IAT) is greater than -18°C (-0.4°F).
^ IAT is no more than 90°C (194°F).
^ The difference between ECT and IAT reading are less than 90°C (194°F).
^ Purge DC is no more than 0%.
^ MAP is at least 20 kPa (6 Hg).
^ Throttle position is between 5% and 60%.
^ Engine speed is between 800 RPM and 3000 RPM.

ACTION TAKEN (VCM-A WILL DEFAULT TO)
VCM-A will turn "ON" the Malfunction Indicator Lamp (MIL) (Service Engine Soon) after two consecutive driving cycles with the fault active.

DTC P1441 WILL CLEAR WHEN
The VCM-A will turn the MIL "OFF" after three consecutive trips without a fault condition present. A history DTC will be cleared if no fault conditions have been detected for forty warm-up cycles [coolant temperature has risen 22°C (40°F) from start-up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle] or the Tech 1 clearing feature has been used.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. When commanded by the Tech 1 scan tool, the EVAP canister purge solenoid valve should make a "clicking" noise. This verifies if the VCM-A has control of solenoid valve.
2. The canister purge vacuum switch is normally closed when no vacuum (purge) is present. With the key "ON" and the engine "OFF," there shouldn't be any vacuum (purge) present in the EVAP system.
3. Determines if the reason the EVAP canister purge solenoid valve could not be commanded was the result of a faulty solenoid, faulty wiring or faulty VCM-A.
4. Determines if the canister purge vacuum switch, wiring or VCM-A is at fault.
5. The VCM-A supplies a 5 volt reference to the canister purge vacuum switch on CKT 416. This step determines if the wiring or VCM-A is at fault.
6. If the 5 volt reference was not available to the canister purge vacuum switch and no other DTCs were set, then the connection is faulty or the circuit is open between the sensor and the wiring splice from the 5 volt reference circuit

DIAGNOSTIC AIDS
An "Intermittent" problem may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.

Refer to Intermittents. - Intermittent Malfunctions