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Engine Code P0440


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I have read several posts concerning engine code P0440; however, I have not seen any that address the problem I had with my 1999 RX300. When this code appeared I started reading and checking the recommendation that were posted; changing gas cap several times (aftermarket to OEM to another aftermarket), checking vacuum lines, replacing O2 sensors etc….this code would keep reappearing . I kept driving it until finally the real culprit showed up. The fuel line that attaches to the fuel injector rails and connects via quick connect just in front of the firewall under the brake booster started spewing fuel under pressure (35-45 psi). I guess in the beginning the leak was just enough to interrupt the sealed system but not enough to leak fuel (go figure). Since I had the air filter box and throttle body removed in order to replace the fuel line I also replaced my spark plugs with E3s. I have driven over 400 miles and no check engine light. My gas millage and power has increased noticeably. The dealer said that they had never replaced that section of the fuel line on any RXs…just my luck…. Here is the link that I found the parts....also has parts breakdown for all categories.

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  • 1 year later...

A code P0440 could mean one or more of the following has happened:

  • The gas cap is not installed or working properly
  • The purge solenoid has failed
  • The canister is plugged and not working properly

try use code scanner clear it.


never say goodbye!


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  • 1 year later...

Hi Paulenka 1. I have been chasing the P0440 problem with so many changes and could not determine the root cause of it. This code eventually kicked off after Firestonre replace the air filter. I replaced the gas cap and still nothing and i am not getting the swoosh sound when i open the gas cap to fuel gas. I dont know what else to check. Pls help driving me crazy. I also checked the hose from the air filter going to the canister, looks good too. I replaced the o2 sensor on B1S1. Where is the purge valve located and can i replace it or test it to confirm if it is malfunctioning. Thanks

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