Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Evaporative emission control
system pressure sensor / Monitor description
Toyota Corolla (E120): Monitor description
Dtc p0451, p0452 or p0453 is recorded by the ecm when the vapor pressure sensor malfunctions.
P0451
The ecm senses pressure in the fuel tank using the vapor pressure sensor. The ecm supplies the sensor with a regulated 5 v reference–voltage and the sensor returns a signal voltage between 0.5 V and 4.5 V according to the pressure level in the fuel tank.
When the pressure in the fuel tank is low, the output voltage of the vapor pressure sensor is low. When it is high, the output voltage is high.
For this dtc p0451, the ecm checks for a ”noisy” sensor or a ”stuck” sensor.
The ecm checks for the ”noisy” sensor by monitoring the fuel tank pressures when the vehicle is stationary and there should be little variation in the tank pressure. If the indicated pressure varies beyond specified limits, the ecm will illuminate the mil and a dtc is set.
The ecm checks for the ”stuck” sensor by monitoring the fuel tank pressure for an extended time period.
If the indicated pressure does not change over this period, the ecm will conclude that the fuel tank pressure sensor is malfunctioning. The ecm will illuminate the mil and a dtc is set.
P0452 and p0453
The ecm senses pressure in the fuel tank using the vapor pressure sensor. The ecm supplies the sensor with a regulated 5 v reference–voltage and the sensor returns a signal voltage between 0.5 V and 4.5 V according to the pressure level in the fuel tank.
When the pressure in the fuel tank is low, the output voltage of the vapor pressure sensor is low. When it is high, the output voltage is high.
If the output voltage of the vapor pressure sensor is out of the normal range, the ecm will determine that there is a malfunction in the sensor or sensor circuit.
When pressure indicated by the vapor pressure sensor deviates below –3.999 Kpa (–30 mmhg) or above 1.999 Kpa (15 mmhg), the ecm interprets this as a malfunction in the vapor pressure sensor. The ecm will turn on the mil and a dtc will be set.
Monitor strategy
P0451
P0452 and p0453
Typical enabling conditions
P0451
P0452 and p0453
Typical malfunction thresholds
P0451
P0452 and p0453
Wiring diagram
Refer to dtc no. P0441
Other materials:
Dtc check/clear
Notice:
if there is no dtc in the normal mode, check the pending
fault code using the continuous test results
function (mode 7 for sae j1979) on the obd ii scan
tool or the hand–held tester.
Hand–held tester only:
when the diagnosis system is switched from the normal
mode to the ...
Hood
Adjustment
Hint:
since the centering bolt is used as a hood hinge and hood lock
set bolt, the hood and hood lock can not be adjusted with it on.
Substitute a bolt with washer for the centering bolt.
1. Inspect hood sub–assy
Check that the clearance is within the standard value.
...
On–vehicle inspection
1. Inspection throttle body idle speed control valve assy
Notice:
it is impossible to check the resister value and the operation
of isc valve by itself, because the isc valve
has an ic circuit inside it, which transforms the duty
signal from the ecm to the derive signal.
After check ...