Fuel System > Engine Control System > P0444 Evaporative Emission System-Purge Control Valve Circuit Open

Component Location

General Description

The evaporative emission control system prevents hydrocarbon (HC) vapors from the fuel tank from escaping into the atmosphere where they could form photochemical smog. Gasoline vapors are collected in the charcoal canister. The PCM controls the Purge Control Solenoid Valve (PCSV) to purge any collected vapors from the canister back to the engine for combustion. This valve is actuated by the purge control signal from the PCM and controls fuel vapor from the canister to the intake manifold.

DTC Description

Checking output signals from PCSV every 10 sec. under detecting condition, if signals indicating open or short to ground in the circuit are detected for more than 5 sec., PCM sets P0444. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition

Item

Detecting Condition

Possible cause

DTC Strategy

•	Open, short to ground

•	Poor connection

•	Open or short to ground in harness

•

PCSV

•

PCM

EnableConditions

•	Engine running

•	11V ≤ Battery voltage ≤ 16V

•	Above enable conditions are met > 0.5 sec.

Threshold value

•	Open or short to ground

DiagnosisTime

•	Continuous (More than 5 sec.failure for every 10 sec.test)

MIL On Condition

•	2 driving cycles

Specification

Item	Coil resistance(Ω)
PCSV	19.0 ~ 22.0Ω (at 20°C / 68°F)

Schematic Diagram

Signal Waveform And Data

The Purge Control Solenoid Valve(PCSV) is open or closed by PCM and vacuum of intake manifold. At opening, fuel vapor from canister enters into intake manifold. To prevent vacuum from forming inside canister, PCM controls to open it. This photo shows the signal waveform of PCSV operating normally.

Monitor DTC Status

Check DTC Status

(1)	Connect scantool to Data Link Connector(DLC).

(2)

IG "ON".

(3)	Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.

(4)	Read "DTC Status" parameter.

(5)

Is parameter displayed "Present fault"?

	▶ Go to "Terminal and connector inspection" procedure.
	▶ Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

Terminal And Connector Inspection

1.	Many malfunctions in the electrical system are caused by poor harness and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
	▶ Go to " Power Circuit Inspection " procedure.

Power Circuit Insepction

■ Check voltage

1.	IG "OFF" and disconnect PCSV connector.

2.	IG "ON" and ENG "OFF"

Measure voltage between power terminal of PCSV harness connector and chassis ground.

Specification : B+

Is the measured voltage within specification ?

	▶ Go to "Control Circuit Inspection" procedure.
	▶ Repair open or short to ground in harness, and go to " Verification of Vehicle Repair" procedure.

Control Circuit Inspection

■ Check short to battery in harness

1.	IG "OFF" and disconnect PCSV connector and PCM connector.

Measure resistance between control terminal of PCSV harness connector and chassis ground.

Specification : Infinite

Is the measured voltage within specification?

	▶ Go to "Check open in harness" as follows.
	▶ Repair short to ground in harness, and go to " Verification of Vehicle Repair" procedure.

■ Check open in harness

1.	IG "OFF" and disconnect PCSV connector and PCM connector.

Measure resistance between control terminal of PCSV harness connector and PCSV control terminal of PCM harness connector.

Specification : Below 1Ω

Is the measured resistance within specification?

	▶ Go to "Component Inspection" procedure.
	▶ Repair open in harness, and go to "Verification of Vehicle Repair" procedure.

Component Inspection

■ Check PCSV

1.	IG "OFF" and disconnect PCSV connector.

Measure resistance between power and control terminals of PCSV connector.(Component side)

Specification : 19.0 ~ 22.0Ω ( at 20°C/ 68°F)

Is the measured resistance within specification?

	▶ Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure..
	▶ Substitute with a known - good PCSV and check for proper operation. If the problem is corrected, replace PCSV and go to "Verification of Vehicle Repair" procedure.

There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. After testing PCM on the vehicle, use this function to reuse the PCM on the others

Verification Of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.

1.	Connect scantool and select "DTC" button.

2.	Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions

3.	Read "DTC Status" parameter

Is parameter displayed "History(Not Present) fault"?

	▶ System performing to specification at this time. Clear the DTC
	▶ Go to the applicable troubleshooting procedure.