I keep getting evap codes and I’ve replaced the purge valve and the vsv valve on the air box. I even replace the connector on the vsv valve cause it was fucked up but I decided to use a test light on it and one side of the terminal is dimmer on the test light. I went down the harness with a test light as far as I could reach and everywhere the light was super dim.
im not no electrician so idk if that’s normal or not and it’s like that cause the circuit is off. But anyone have any idea how to get rid of this issue? (Ignore the catalyst codes lmao)

 

It could be the voltage is lower on that terminal and supposed to be. Make sure there is no vacuum leak as these hoses get brittle.

 

the P0430 (equivalent to P0420 different bank) was something we chased for 5 years on my wife's GM because I refused to pay $4,000 for a new CAT and we do have emissions testing. But searching online with her particular vehicle people all said nobody likes bad news but that's what it is (YouTube would purport it's not). So with our LS430's dunno, hopefully it's not like GM.

 

What diagnostic references are you using? The diagnostic sections for P0441/P0446, from the 2002 FSM are attached.

 

I already checked the dealer manuals. I’m just curious on why one side of the pigtail is dimmer than the other when I use a test light. I’m pretty sure it’s electrical but I’m hoping it’s not and someone has similar experience

 

I bet that is ok as the voltage would not be the same on each side of the sensor.

 

Here you go!

https://charm.li/Lexus/2002/LS%20430...%20Inspection/

 

thank you but already used charm. Plus it’s not the purge valve that’s the issue it’s the charcoal canister vsv valve on the air box

 

P0420/P0430 are almost always due to cracks in the Y-pipe where it bolts to the CAT, and not a fault in the CAT itself.
Air is being sucked into the exhaust system so the downstream sensor is detecting more oxygen than the upstream sensor.

For the rest of the codes I would check all of the hoses that connect to the Evap system, and also make sure that the gas cap is sealing (it should hiss when you unscrew it immediately after driving it).

 

Had EVAP codes on my Dad's 2003. Corrected by replacing the related rubber hoses and the "Feed Line" P/N: 23818-46110 (under the engine cover). As the engine has over 250K, I also replaced the PVC Valve, Hose, and Grommet. (they looked original) so far so good but if the issues happens again I'll smoke check the whole EVAP system for leaks.....

 

P0420 and P0430 also have a high probability of showing up when any codes related to emissions show up. Whenever you look at the flow chart for those codes it always says if there are any other codes to address those first.

The UZ vehicles have 3 VSVs. The one on the intake, the airbox, and the one mounted to the charcoal canister. For some reason Toyota does not list a part number for the valve on the canister, but 90910-12264 is an identical replacement. On my LX the valve mounted to the charcoal canister had gone bad and I used Wells 2M1257 to fix it. So check this valve as well.