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(0.05V) within 3min. , ECM sets P0451. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition





Specification





Diagnostic Circuit Diagram





Signal Waveform & Data








Fig.1) Normal waveform of FTPS at idle.
Fig.2) Normal data of FTPS at idle.

Monitor Scantool Data

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"?�






Component Inspection

1. IG "OFF" & connect scantool.
2. ENG "ON" and Race the accelerator pedal at idle and Monitor "FTPS" parameter is changing while PCSV is operating on the service data.

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









Fig.1) Sample data at idle with no acceleration (It can be different based on purging state)
Fig.2) Sample data at idle with acceleration (It can be different based on purging state)
3. Does the FTPS change while racing the accelerator pedal at idle ?






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