P0451

P0451

Component Location:

General Description
The evaporative emission control system prevents hydrocarbon vapors from escaping from the fuel tank into the atmosphere where they could form photochemical smog. Gasoline vapors are collected in the charcoal canister. The Fuel Tank Pressure Sensor (FTPS) is an integral part of the evaporative monitoring system. The ECM monitors the FTPS signal to detect vacuum decay and excess vacuum. The FTPS measures the difference between the air pressure inside the fuel tank and outside air pressure to check the purge control solenoid valve operation and for leak detection in the evaporative emission control system by monitoring pressure and vacuum levels in the fuel tank during the purge control solenoid valve operating cycles.

DTC Description
Checking output signals of tank pressure under detecting condition, if the tank pressure does not change less than 0.2 (0.05 V) within 3 min., PCM sets P0451 MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition:

Specification:

Schematic Diagram:

Monitor DTC Status
1. Check DTC Status
1. Connect scantool to Data Link Connector(DLC).
2. IG "ON".
3. Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F5(INFO) to check DTC's information from the DTCs menu
4. Read "DTC Status" parameter.






5. Is parameter displayed "Present fault"?

YES
a. Check hose between canister and tank for damage, restriction, and proper connection. Repair or replace as necessary and then, go to "Component Inspection" procedure.

NO
a. Fault is intermittent caused by PCM memory was not cleared after repair.
Erase DTC and go to "Verification of Vehicle Repair" procedure.

Component Inspection
1. IG "OFF" & connect scantool.
2. ENG "ON" and race the engine at idle.
3. Monitor "FTPS" data while PCSV is operating.

Specification : Fuel Tank Pressure is O.K if pressure changes more than 0.2 while racing accelerator pedal.






4. Does the FTPS change while racing the engine at idle ?

YES
a. Fault is intermittent. Drive the vehicle to satisfy the enable condition then, go to "Verification of Vehicle Repair" procedure.

NO
a. Substitute with a known - good FTPS and check for proper operation. If the problem is corrected, replace FTPS and go to "Verification of Vehicle Repair" procedure.

Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode
2. Press F5(INFO) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
3. Read "DTC Status" parameter
4. Is parameter displayed "History(Not Present) fault"?

YES - System performing to specification at this time. Clear the DTC.

NO - Go to the applicable troubleshooting procedure.