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.
If PCM detects the abnormal signal input of FTPS, ECM sets DTC P0451.
Item
Detecting Condition
Possible cause
DTC Strategy
Rationality check
Hose between Canister and Tank is not connected.
Faulty FTPS
Case1
Enable
Conditions
Vehicle speed < 19mph
Ambient Temp > 0?(32?)
Accel. Pedal = 0%
Threshold
Value
? FTP > 1.0 kPa
Diagnostic
Time
15 sec
Case2
Time after engine start > 4.0s
15%< Fuel level < 85%
Fuel tank pressure > 3.5 kPa or < -3.5 kPa
14 sec
Case3
? Canister Purge flow > 1.6kg/h
Intake manifold press./amb. Press < 0.62
? FTP < 0.03 kPa
MIL On Condition
2 Driving Cycles
Pressure (kPa)
Output Voltage (V)
-6.67 (26.7VAC)
0.5
0
2.5
6.67 (-26.7VAC)
4.5