I have a problems with 01 lexus RX300 check engine code PO440 PO446.I replace gas cap and Evap vacum switch. But the check engine still on after 100 miles of driving. I need help..................

 

P0440 Evaporative Emission Control System Malfunction

Could be any of the following:

-Vapor Pressure Sensor
-Fuel tank cap incorrectly installed
-Fuel tank cap cracked/damaged
-Cracked vacuum hose, holed, blocked, damaged or disconnected between the vapor pressure sensor and and VSV for Vapor Pressure Sensor and/or betweeen the VSV for Vapor Pressure Sensor and Charcoal canister
-Cracked hose or tubed, holed damaged or loose seal toward the fuel tank
-Cracked, holed or damaged fuel tank
-Cracked, holed or damaged charcoal canister

P0446 Evaporative Emission Control System Vent Control Malfunction
-Open or short in VSV circuit for vapor pressure sensor
-VSV for Vapor pressure sensor
-open or short in vapor pressure sensor circuit
-vapor pressure sensor
-open or shot in VSV circuit for EVAP
-VSV or EVAP
-Vacuum hose cracked, holed, blocked, damaged or disconnected among Vapor Pressure Sensor, VSV for Vapor Pressure Sensor, VSV for EVAP, Charcoal Canister, Fuel Tank, Fuel Tank Over Fill Check Valve
-Cracked, holed or damaged charcoal caniseter
-Cracked/damaged over fill check valve

MY TWO CENTS:

1st cent: there was a condition detected (like and equivalence with atmospheric pressure and the pressure in these lines) for a brief moment and one needs to reset the ECU. Pull the negative battery cable off or as we have mentioned, pulling the EFI fuse shown below with the vehicle off for a few seconds and then putting it back in. That should reset the light, but if it comes back on again, then it is my 2nd cent.

2nd cent: something as mentioned above is messed up. Iwould pinpoint the gas cap first, but take a look at the hoses on the air box to make sure they are tight and no leaks. The third issue is the charcoal canister. These things can go. Basically any hoses around there that have a leak reduce pressure to a point where they equal atmospheric pressure and then the CEL pops on.

 

Document the radio settings, AM & FM.

Remove the EFI 20 Amp (yellow) fuse in the fuse box under the hood. Use the white tool provided on the fuse box lid. Replace it after a minute or two, returning the tool to the lid.

Or disconnect the battery ground for twenty or so minutes... (10mm)

This action should reset the Check Engine Lamp on the dash.

Try not to fill the tank to the top for the next few fills, hoping the charcoal filter will clear itself.

Insure the EVAP test point green cap is snug, but not too tight as the cap might crack. It is located to the inside or left-rear of the engine air filter box.

If the problem persists, check the hoses on the VCV (vacuum control valves), near the charcoal vapor assembly. It is located under a black plastic cover, under the RX exterior in the location of the spare tire.

Use care when removing the small vacuum hoses. Work loose the edge of the hose before trying to turn it on the valve nipple.

If the hoses are not cracked and leaking, chances are the charcoal canister needs to be replaced.

Inspect it for a part number, or contact Toyota for one used in a 2001 Highlander

 

U know anyway u can check the charocal canister. sometime i drive 500 or 600miles the light came back on.

 

The checkout procedure I have reviewed requires a dealer service tool, a low pressure compressor, vacuum pump and specialized connection tools.

 

Take a look at the hoses and lines at this location.

 

Another proceedure, see towards the end of the document.

 

If you can get our valve cover off, you fill find the VSV for EVAP here and a whole bunch of the other sensors mentioned just to the right of this piece along with hoses and lines.

 

Right underneath this general location is where I was alluding to in the last email. Perhaps someone here has a picture of what it looks like underneath as I don't have my tools with me to take the cover off.

 

Check hose on top half portion of air filter housing. When replacing air filter, if top housing is pulled to far it will pull evap hose loose from canister closed valve. Evap VSV malfunctions generally set P0441

 

hey thank alots found out the hose on the air box came off. u save me alots of money the dealer want to charge me 600 dollars to fix the problems. I put 400 miles already the check engine hasn't come on. peace out............

 

Does anyone know where the canister closed valve is located? I have the inexpensive repair manual (Haynes) that says it is located "in the engine compartment on the backside of the air filter housing." I am unable to locate it. I have found the purge valve on top of the intake manifold. I metered the coil and then verified it was opening and closing by simultaneously sucking on the outlet while applying 12 volts to the coil. Valve works fine. I'd like to do this to the canister closed valve if I could locate it.

I am trying to diagnose a P0446. These two valves seem like the two easiest things to check (besides gas cap). If only I could find it!

 

I think the vacuum line that goes to that valve comes right off the air cleaner. Sent you a PM.

 

Hey dcsports, don't fret. I had the same CE code about a year ago and reset it with a scan tool and it has not come back... Do some research, it appears Toyota is aware that this CE code is common problem and not necessarily indicative of defective part.. Lots have had the same code only to spend big money on fixes and problem comes back....

Save your money and reset it. You'll be surprised when the CE dosen't come back for a year or more....

Your welcome!

 

To all,

I have 2001 RX300 and had Trac Off, VSC and Engine Light go off. I had following codes:

P0440 (as in title) and B2796.

I was told or read that P0440 could have been cause because we ran the car low on gas, near empty.

B2796 No Comm in Immobilizer System -- I was told this could be caused because the key broke off with the key in the ignition and the plastic head broke off. The car, because of the anti-theft would not start properly until we glued the key back together.

Both lights are off.

I will check hoses and other items suggested in this thread. But my questions is could driving the car low on gas - EMPTY case the P0440 code?

I will get a new key from the dealer because I was told this could cause a short in that circuit.

Does anybody know about B2796?

Thanks,