Fuel System > Engine Control System > P0448 Evaporative Emission System

Component Location

General Description

The evaporative emissions 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 Canister Closing Valve (CCV) closes off the air inlet into the canister for leak detection of the evaporative emission system. The CCV also prevents fuel vapors from escaping from the canister. When the engine purges the HC vapors from the canister, the clean air comes into the canister through the canister air-filter and the CCV.

DTC Description

Checking output signals from CCV every 10 sec. under detecting condition, if signals indicating short to battery in the circuit are detected for more than 5 sec., PCM sets P0448. 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

•	Detects a short to battery

•	Poor connection

•	Short to battery in CCV circuit

•	Faulty CCV

•	Faulty PCM

EnableConditions

•	Engine Running

•	11V ≤ Ignition Voltage ≤ 16V

•	Enable Time delay ≥ 0.5sec.

Threshold value

•	Short to battery

DiagnosisTime

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

MIL On Condition

•	2 driving cycles

Specification

Item	Specification
Coil Resistance(Ω)	15.5 ~ 18.5 Ω at 20°C(68°F)

Schematic Diagram

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 " Control Circuit Inspection " procedure

Control Circuit Inspection

■ Check short in harness

1.	IG "OFF" and disconnect CCV connector.

Measure resistance between power and control terminals of CCV harness connector.

Specification : Infinite

Is the measured resistance within specifications?

	▶ Go to " Component Inspection " procedure.
	▶ Check short in harenss. ▶ Repair or replace as necessary and then, go to " Verification of Vehicle Repair" procedure.

Component Inspection

Check CCV

(1)	Ignition "OFF"

(2)

Measure resistance between power and control terminals of the CCV connector.

Specification: Approx. 15.5 ~ 18.5Ω (20°C(68°F))

(3)

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 CCV and check for proper operation. ▶ If the problem is corrected, replace CCV 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.