engine check light !!! (codes # PO442 & PO456)

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Thread: engine check light !!! (codes # PO442 & PO456)

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    Supporter EIDER's Avatar
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    Default engine check light !!!

    mine came on again after i had just reset it via neg. removel . 8500 , then 9025 mi. i have access to a tester and codes came up # po 442 and po 456 , i went to other theards and lon's garage and figured out 442 means gas cap. anybody know what 456 means ?? or is it time to call dealer and or take truck in E.

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    Quote Originally Posted by EIDER
    mine came on again after i had just reset it via neg. removel . 8500 , then 9025 mi. i have access to a tester and codes came up # po 442 and po 456 , i went to other theards and lon's garage and figured out 442 means gas cap. anybody know what 456 means ?? or is it time to call dealer and or take truck in E.
    P0442, P0456
    The vapor pressure sensor, VSV for EVAP and VSV for CCV are used to detect abnormalities in the evaporative emission control system. The ECM judges whether there abnormalities exit in the evaporative emission control system, based on the signals from the vapor pressure sensor. If evaporative emissions leak from the components specified within the dotted line Fig. 1 or the vapor pressure sensor malfunctions, ECM records DTC P0442 or P0456.

    DTC Detecting Condition
    After cold engine start.
    After VSV for EVAP operation, the VSV for EVAP is turned off sealing the vacuum in the system and the ECM begins to monitor the pressure increase.
    Some increase is normal. A very rapid, sharp increase in pressure indicates a leak in the EVAP system and sets the DTC P0442. This monitoring method is also able to distinguish what is called the small or very small leak detection.(DTC P0456) A pressure rise just above normal indicates a very small hole.
    (2 trip detection logic)

    Trouble Area
    Vacuum hose cracks, holed blocked, damaged or disconnected
     Fuel tank cap incorrectly installed
     Fuel tank cap cracked or damaged
     Open or short in vapor pressure sensor circuit
    Vapor pressure sensor
     Open or short in VSV circuit for EVAP
     VSV for EVAP
     Open or short in VSV circuit for CCV
     VSV for CCV
     Fuel tank cracked, holed or damaged
     Charcoal canister cracked, holed or damaged
     Fuel tank over fill check valve cracked damaged
     ECM


    Regarding P0442 see TSB's EG019-03 and EG020-03
    EG019-03 - Some 2003 – 2004 model year Tundra vehicles may experience a MIL “ON” condition with DTC P0442 – Evaporative Emissions Control System Small Leak – due to an irregularity in the Fuel Filler Tube sealing surface. An improved Fuel Filler Tube has been developed to correct this condition.

    EG020-03 Some 2003 and 2004 model year 4Runner, Sienna and Tundra vehicles may experience a M.I.L. “ON” condition with DTC P0441, P0442 and/or P0446 due to a sticking EVAP Purge Vacuum Switching Valve (VSV). The EVAP Purge VSV has been improved to correct the M.I.L. “ON” condition.

    NOTE: You should not disconnect your battery to reset the check engine light. The Check Engine Light or Malfunction Indicator Lamp (MIL) comes on when the ignition switch is turned ON and the engine is not running. When the engine is started, the MIL should go off. If the lamp remains on, the diagnosis system has detected a malfunction or abnormality in the system.

    OBD II regulations require that the vehicle's on-board computer lights up the Malfunction Indicator Lamp (MIL) on the instrument panel when the computer detects a malfunction in the emission control system/components or in the power train control components which affect vehicle emissions, or a malfunction in the computer. In addition to the MIL lighting up when a malfunction is detected, the applicable Diagnostic Trouble Codes (DTC) prescribed by SAE J2012 are recorded in the ECM memory. If the malfunction does not reoccur in 3 consecutive trips, the MIL goes off automatically but the DTCs remain recorded in the ECM memory.

    *2 trip detection logic: When a malfunction is first detected, the malfunction is temporarily stored in the ECM memory. (1st trip) If the same malfunction is detected again during the second drive test, this second detection causes the MIL to light up. (2nd trip) (However, the ignition switch must be turned OFF between the 1st trip and 2nd trip.).
    ~Glenn
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    "To err is human. To arrr is pirate."

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    WOW !!!! thanks alot Mr Bird, i'll try to figure out whats wrong . E .

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    Quote Originally Posted by EIDER
    mine came on again after i had just reset it via neg. removel . 8500 , then 9025 mi. i have access to a tester and codes came up # po 442 and po 456 , i went to other theards and lon's garage and figured out 442 means gas cap. anybody know what 456 means ?? or is it time to call dealer and or take truck in E.
    What did you find out about the PO codes as far as what was wrong with your EVAP? My check engine light came on recently and I had my ECU read for the codes. It came back with the following:

    P0441 - Evaporative Emission Control System Incorrect Purge Flow
    P0446 - Evaporative Emission Control System Vent Control Malfunction

    Anyone have a diagram or something to view to determine what I need to look for and fix this?

    Thanks?

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    Default ??? Tube

    Noticed this tubing(circled in yellow) unconnected but, from what. This is on the driver side. Looked at chrislloyd's tundra and found out that it connects to a rubber hose and leads into the frame where it is connected to a plastic valve/connector of some sort. This tubing starts from the EVAP system. So, I'm thinking this is the cause of my CEL. What does this tube do when it's connected to the frame?
    Upper tube
    Tube at frame

    MODERATOR NOTE: Photos too large to include in post; changed to links to improve thread loading speed.
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    Cool Re: engine check light !!! (codes # PO442 & PO456)

    p0456 - according to my little book that came with my code scanner,
    its a generic code and its evap emission system leak (small leak)

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    Default Re: engine check light !!! (codes # PO442 & PO456)

    i just change my gas cap to a locking one from kragen and after a few trips engine light came on got the reading from an obdII reader and got p0456 very small leak in evap , but i to tight so i will try to see if it does sopposed to come off or not or i should replace with the original by the way it's a new tundra less than 1k miles if any one would know because the locking cap its tighter.

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    Default Re: engine check light !!! (codes # PO442 & PO456)

    Some aftermarket caps may not offer a proper seal as most come form offshore sources. The small leak code (po456) is most likely due to a poor seal. It is best to put on an OE cap and be done with it. Did your truck not come with a locking gas door anyway ?

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