P0451

DTC P0451 EVAPORATIVE EMISSION CONTROL SYSTEM PRESSURE SENSOR/SWITCH RANGE/PERFORMANCE

CIRCUIT DESCRIPTION

DTC Detection Conditions:

The vapor pressure sensor, VSV for CCV (Vacuum Switching Valve for Canister Closed Valve) and VSV for EVAP (Evaporative Emission) are used to detect abnormalities in the EVAP control system.

The ECM determines whether there is an abnormality in the EVAP control system based on the vapor pressure sensor signal.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

DTC P0451, P0452 or P0453 is set by the ECM when the vapor pressure sensor malfunctions.

P0451
The ECM monitors the fuel tank internal pressure using the vapor pressure sensor. The ECM supplies the sensor with a regulated 5 V reference voltage, and the sensor provides the ECM with a signal voltage of between 0.5 V and 4.5 V as feedback, depending on 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.
- The ECM sets DTC P0451, if either one of the following conditions applies:
The ECM checks for noise in the sensor by monitoring the fuel tank internal pressure when the vehicle is stationary. When the vapor pressure sensor is functioning normally, it indicates a small variation in pressure. If the indicated pressure variation deviates from the predetermined level, the ECM illuminates the MIL and sets the DTC.

- The ECM checks for a stuck sensor by monitoring the fuel tank internal pressure for an extended time period. If the indicated pressure value does not vary over the time period, the ECM interprets this as a malfunction in the sensor, and illuminates the MIL and sets the DTC.

Wiring Diagram:

Step 1 - 2:

Step 3:

INSPECTION PROCEDURE

HINT:
- If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
- If any of DTC P0441, P0446 or P0451 are set simultaneously with DTC P0442 or P0456, first troubleshoot DTC P0441, P0446 or P0451. If no malfunction is detected, troubleshoot DTC P0442 or P0456 next.
- Read freeze frame data using a hand-held tester or OBD II scan tool. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.
- If the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the vapor pressure sensor.