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:
No sound is heard from speaker in all modes
Wiring diagram
Inspection procedure
1 Check lcd (liquid crystal display) for lighting
Lcd illumination check
turn the ignition switch acc.
Turn the radio receiver assembly on.
Standard: lcd illumination of the radio receiver assembly light.
2 Control fader and ...
Timing gear cover oil seal
Replacement
1. Remove engine under cover rh
2. Remove front wheel rh
3. Remove fan and generator v belt
Turn the v–ribbed belt tensioner slowly clockwise and
loosen it. Then, remove the fan and generator belt v and
put back the v–ribbed belt tensioner little by little and fix
it ...
Body panel undercoating areas
Apply pastar uwe or pastar uc to the chassis, floor underside, sheet metal
fitting weld points of the body, and
inside of the wheel house to prevent rust and noise, as well as protect the body
from flying rocks.
Hint:
work must be performed while wearing the appropriate protective ...