96 2.7 5 speed p0450 code?

Discussion in '1995 - 2004 Toyota Tacoma' started by Boss102372, Jul 21, 2013.

  1. Boss102372

    Boss102372 New Member

    I just purchased a 96 Tacoma 4x4 2.7 5 speed, and I got the check engine light read. It gave me a p0450 code and I was wondering if 1. What this code means and 2. If there is a vacuum diagram available so I can re do the vacuum system?
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  3. byrd

    byrd Moderator Moderator

    OBD II Fault Code

    OBD II P0450

    Fault Code Definition

    Evaporative Control System Pressure Sensor Malfunction


    Check Engine Light will illuminate
    In most cases, there are no adverse conditions noticed by the driver
    In some cases, there may be a noticeable fuel odor caused by the release of fuel vapors

    Common Problems That Trigger the P0450 Code

    Defective Fuel Tank Sending Unit
    Defective or damaged Fuel Tank
    Defective Fuel Tank Pressure Sensor, wiring, or computer

    Common Misdiagnoses

    Fuel Cap
    Evaporative Purge Valve
    Evaporative Vent Valve

    Polluting Gases Expelled

    HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog

    The Basics
    The Fuel Tank Pressure Sensor is a device that tracks any positive or negative pressure changes in the Fuel Storage or Evaporative Control (EVAP) system. It constantly relays this pressure information to the Powertrain Control Module (PCM). The Fuel Tank Pressure Sensor is located on top of the Fuel Tank, or on or near the Fuel Pump and Fuel Gauge Module.

    Want to Learn More?
    The Evaporative Control system Pressure Sensor code sets when the readings of the Pressure Sensor remain at a fixed value and do not change for ten seconds of vehicle operation after a cold start.

    P0450 Diagnostic Theory for Shops and Technicians
    The Code P0450 indicates that the Evaporative Pressure Sensor output value is not changing during the EVAP Monitor test and/or the operation of the vehicle. This code uses "two trip" logic, which means that the fault condition must be present during two successive cold starts and vehicle operation.

    Common Tests for the Evaluating the Fuel Tank Pressure Sensor

    Retrieve the code and write down the freeze frame information to be used as a baseline to test and verify any repair.
    Pay very close attention to the Fuel Tank Pressure readings by observing its data stream on a scan tool. Does the Fuel Tank Pressure Sensor work properly? If it doesn't, the system will think that no vacuum is being created when, in fact, there is a vacuum being created that the Fuel Tank Pressure Sensor is unable to read. The Fuel Tank Pressure Sensor is the primary feedback sensor that the Powertrain Computer relies on for the leak test data.
    Inspect and test the Fuel Pressure Sensor wiring. Verify that there is a 5-volt reference signal from the PCM, a good ground, as well as a good signal return circuit to the PCM.
    While observing the data stream change (or lack there of) on a scan tool, test the Pressure Sensor with a Vacuum Gauge while it is connected to the wiring harness.
    If all of the above test results are within spec, then the problem may reside in the PCM itself.

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