EVAP code P0440

Tiny
CONCHSALAD
  • MEMBER
  • 2000 LEXUS RX 300
  • 3.0L
  • V6
  • 2WD
  • AUTOMATIC
  • 167,000 MILES
Customer states : vehicle began with the code p0440(2).

I replaced the fuel cap with Lexus parts. No visible rust or wear on the filler neck. After replacing, the code read-
p0440(1).
Inspected all of EVAP system for cracks, loose hoses, etc-none found.
Performed smoke test, oil filler cap was leaking badly, replaced with Lexus parts. There are two small leaks, photos provided, other than those two, no more leaks were found.
No oil leaks of any kind.
Does not burn excessive oil.
Does not run hot.
Tested all valves on the EVAP with direct 12v current, they all work.
Vehicle has excessive fuel consumption (30-40 miles a tank).
All filters on vehicle are new.
Replaced vacuum switch valve near the air filter box.

I am been working on my cars for over 20 years, so I know a few things. Cant figure this one out.
I am NOT good with a multi meter, ONLY BASIC.

Thank you for your support!
AW
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Wednesday, August 27th, 2025 AT 8:35 PM

2 Replies

Tiny
MECHTRIX
  • MECHANIC
  • 382 POSTS
Do you ever smell gas sounds like you checked just about everything you might want to check the top of the tank might not be venting properly check charcoal can could be 25 years old by now might want to replace it anyway. Also did you check the purg valve in the eng bay? It's common
heres a diagram plaese click below good luck
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Wednesday, August 27th, 2025 AT 9:58 PM
Tiny
MECHTRIX
  • MECHANIC
  • 382 POSTS
Also might want to check the vsv switching vales if you havent yetthere 3 of them one might be stuck open starts drinking gas when that happens also be sure to check the vapor pressure sensor. Heres another diagram with more evap system click down below good luck
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Wednesday, August 27th, 2025 AT 10:02 PM

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