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Lexus RX300. Code P0440

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Lexus RX300. Code P0440 .
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Customer reply replied 4 months ago
History of P0440. Replaced gas cap, purge valve, vapor canister. Smoke tested and repaired/checked vacuum lines. Going on 400 miles, still Evap Not Ready. Needs inspected. My daughter's car. Any tricks or things I need to check.
Answered in 10 minutes by:
3/17/2018
David Craig
David Craig, Auto Mechanic
Category: Lexus
Satisfied Customers: 5,797
Experience: Owner/Mechanic at 3D Automotive
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Hi my name is ***** ***** I'll be more than happy to assist you, Please allow me a few minutes to review your information. Thank you.

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Customer reply replied 4 months ago
On top of tank?

yes

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Customer reply replied 4 months ago
If it’s bad, wouldn’t it have leaked smoke during the smoke test?

no. it is a valve the is opened or closed. depending on the pressure inside the tank

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Customer reply replied 4 months ago
Wouldn’t that valve throw the p0446 code?

not on your system. there's an early and a late design

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446 is the vsv valve

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Customer reply replied 4 months ago
Please tell me I don’t have to drop the tank to access it.

unfortunately, yes you do

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Customer reply replied 4 months ago
If that vent is bad, shouldn’t it throw the code? Especially reading not ready after 400 Miles?

it is throwing the code P0440

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if you are going to repeatedly question my diagnosis I will gladly open this up to the others.

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Customer reply replied 4 months ago
There is no code. Reads not ready. Just like my initial question states.
Customer reply replied 4 months ago
If you don’t want to answer this forum and you have thin skin, then by all means move on and let someone else help. Geez.

thin skin? please don't not patronize me. replace the vent valve. sometimes you have to do what you don't want to do or aren't capable of doing.

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Customer reply replied 4 months ago
Please refer me to an expert.

I am an expert and I am recommending what to do

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Customer reply replied 4 months ago
You aren’t capable of criticism and you have no idea of who I am.
Customer reply replied 4 months ago
I’ll take door #2, refer me to another expert.

good day

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eric remington
Category: Lexus
Satisfied Customers: 881
Experience: mechanic/service advisor at topline auto
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P0440

DTC P0440: EVAP SYSTEM MALFUNCTION

CAUTION: If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION.

Circuit Description

Vapor pressure sensor, canister closed valve Vacuum Switching Valve (VSV) and pressure switching valve VSV are used to detect faults in EVAP system. ECM determines if a fault is present in EVAP system based on the vapor pressure signal circuit. DTC P0440 is set if EVAP system leak is detected or vapor pressure sensor malfunctions (detection of atmospheric pressure in fuel tank, after vehicle has been driven for 20 minutes). Possible causes are:

  • Faulty vapor pressure sensor.
  • Fuel tank cap installed incorrectly.
  • Fuel tank cap defective.
  • Damaged, disconnected or blocked vacuum hose.
  • Fuel tank damaged.
  • Charcoal canister damaged.
  • Hose between fuel tank and charcoal canister damaged.
  • Open or short in vapor pressure sensor circuit.
  • Fuel tank overfill check valve damaged.
  • Faulty ECM.

NOTE: If DTC P0441, P0446, P0450 or P0451 is output after DTC P0440, perform appropriate diagnostic test first before performing DTC P0440 test.

Diagnostic Aids

Ask customer if fuel cap has been left off or not completely tightened recently. This may cause DTC to be set. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

Diagnosis & Repair

  1. Check with vehicle driver if fuel tank cap was found loose at any time. If fuel tank cap was loose, it probably was cause of DTC P0440 to set. If fuel tank cap was not loose, check for cracks, deformations or loose connections in the following:
    • Fuel tank.
    • Charcoal canister.
    • Fuel tank filler pipe.
    • Hose and tubes around fuel tank and charcoal canister.

    Repair as necessary. If components are okay, go to next step.

  2. Check if fuel tank cap is an original manufacturer's cap. If fuel tank cap is an original manufacturer's cap, go to next step. If fuel tank cap is not an original manufacturer cap, replace cap with a manufacturer's cap.
  3. Check if fuel tank cap is installed properly. Reinstall fuel cap as necessary. If fuel cap is installed properly, go to next step.
  4. Check for damaged fuel tank cap and gasket. Replace fuel cap as necessary. If fuel tank cap and gasket are okay, go to next step.
  5. Remove fuel tank cap. Visually inspect fuel tank filler neck for damage. Replace filler neck as necessary. If filler neck is okay, go to next step.
  6. Check vacuum hoses between vapor pressure sensor and fuel tank, and between pressure switching valve VSV and charcoal canister. Check hoses for correct installation, looseness and damage. Repair as necessary. If vacuum hoses are okay, go to next step.
  7. Check hose and tube between fuel tank and charcoal canister for correct installation and damage. Repair as necessary. If hose and tube are okay, go to next step.
  8. Visually inspect charcoal canister for cracks or damage. Replace canister as necessary. If canister is okay, go to next step.
  9. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 2 (Yellow/Black wire) and No. 18 (Brown wire) at ECM E6 connector. See Figure. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest system.

    NOTE: Vehicle may be equipped with one of 2 different types of vapor pressure sensor. Sensor is mounted on top of fuel tank and may either have 2 vacuum ports (old style) or no vacuum ports (new style).

  10. Locate vapor pressure sensor on top of fuel tank. See Fig 1. Identify type of vapor pressure sensor used. If sensor does not have any vacuum ports, go to next step. If sensor has 2 vacuum ports, disconnect vacuum supply hose from vapor pressure sensor. See Fig 2. Backprobing ECM harness connector, connect voltmeter between terminal No. 17 (Blue/Orange wire) at ECM E8 connector and terminal No. 18 (Brown wire) at ECM E6 connector. See Figure. Connect a vacuum pump to sensor. Voltage should be 3.0-3.6 volts without vacuum applied, and 1.3-2.1 volts with .59 in. Hg (2.0 kPa) applied. If voltage is as specified, go to step 13. If voltage is not as specified, go to step 12.
  11. Backprobing ECM harness connector, connect voltmeter between terminal No. 17 (Blue/Orange wire) at ECM E8 connector and terminal No. 18 (Brown wire) at ECM E6 connector. See Figure. Remove fuel tank cap and note voltmeter reading. If voltage is 3.0-3.6 volts, go to 13. If voltage is not 3.0-3.6 volts, go to next step.
  12. Check for an open or short in wiring harness between vapor pressure sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace vapor pressure sensor.
  13. Check fuel tank and fuel tank overfill check valves for cracks and damage. Overfill check valve is located on top of fuel tank. See Fig 1. Replace fuel tank or overfill check valve as necessary. If fuel tank and overfill check valve are okay, probable cause of DTC P0440 to set was an incorrectly installed fuel tank cap.

    NOTE: Overfill check valve may also be referred to as fill check valve. Cut-off valve may also be referred to as fuel cut-off valve.

Fig 1: Identifying EVAP System Components

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. View Full-Screen

Fig 2: Identifying Vapor Pressure Sensor (Old Style)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. View Full-Screen

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D​IAGNSOTIC A PROCESS OF ELIMINATION GAS CAP AFTERMARKET? ORIGINAL? DOES TANK MAINTAIN PRESSURE

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WH​O SMOKE TESTED? HAS DATA STREAM BEEN ACCESSED

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Customer reply replied 4 months ago
Factory gas cap replaced. Daughter made a statement that the Trac light and engine light would come on at the same time. I’ve replaced almost the entire evap system. Cleared the code and now it has been driven 400 Miles and EVAP is still not ready. No current engine light. ECM? Glitch?
Customer reply replied 4 months ago
Smoke tested by Lexus mechanic. Hooked up scanner and checked each valve. Everything seems to be in working order, but won’t clear the EVAP readiness.

O​K I WILL SEND YOU A SCHEMATIC PICURE OF WHAT COMPONENTS ARE IN THE SYSTEM YOU TELL ME WHAT YOU REPLACED....WHAT ABOURT SCAN READINGS ? DOES ATMOSPHERIC PRESSURE TAKE OVER THE SYSTEM AS OPPOSED TO VACUUM?

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Customer reply replied 4 months ago
Replaced vapor canister, purge valve rail and all lines, checked repaired replaced all vacuum lines, fuel cap. Smoke tested and ran a test on each component seperately. No smoke leaks. No pressure loss. NO ENGINE LIGHT On now. Driven 400 Miles since cleared and replaced, but NOT READY. No lights on. Not Ready for inspection.
Customer reply replied 4 months ago
Is there a manual drive cycle I can put the car through? It has experienced odd electrical glitches this past year. Parasitic draining of the battery. 18 years old, 205k.

so you don't have a code its just that the monitor has not been reset? so you need enable criteria?

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Customer reply replied 4 months ago
Correct. No current codes. Everything seems to be working, but after driving 400 city miles, still not ready for inspection.

you may be abe to access the pressure sensor by taking apart the cover to fuel pump access! now how about that for good news?

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Customer reply replied 4 months ago
I’ll take any news if it leads me to a resolution.

ok right off the bat I know for a fact that the fuel tank needs to be betseen 1/4 ND 3/4THS

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WELCOME TO MY WORLD

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I WILL LOOK UP THE REST OF THE ENABLE CRITERIA...SHOWS TEH DRIVE CYCLE ONE MUST GO THRU...DRIVE IN REVERSE AT 80 MPH HONK HORN THRICE JUST KIDDING BUT ALMOST NOT REALLY ILL HUNT THAT DOWN FOR YOU

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Customer reply replied 4 months ago
Ha. Ever since some weird electrical stuff, I think there is a glitch somewhere. Parasitic drain until I removed some fuse, but some still worked. Then drain until I removed radiofuse, but radio still worked. Now both fuses are in and no drain, but now this. Ha.
Customer reply replied 4 months ago
Dome fuse.

D​IDNT CATCH YOUR NAME SIR BUT COULD YOU GIVE ME AN EMAIL ADRESS WHEN I TRY TO LOAD THE INSTRUCTIONS TO THIS PAGE ITS NOT WORKING FOR SOME REASON

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Customer reply replied 4 months ago

*********** Tim

sent you emails first didn't come out well but ast one did I think...let me know..if you need instructions for access top of tank let me know

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THERE IS AT LEAST ONE ACCESS PANEL ATOP OF TANK THE TRUNK AREA COMPARTMENT HAS ACCESS COVERS. LET ME KNOW WHAT COMPONENT YOU WANT TO TEST REPLACE AND I WIL ADVISE ON HOW TO BEST ACCESS IT

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I​f you have any further needs please feel free to ask even after rating thanks for choosing just answer

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