P0446 code and P0442 code

Hey Folks!

I have a P0446 and P0442 code and I wanted to compile my troubleshooting and all the resources I used to help me find the suspected problem.

My truck is a 2003 Tacoma Double Cab 3.4l 265k

The Check engine light turned on after a long trip on some rough dirt logging roads. I ran my code scanner and it spit out the following codes and descriptions.

P0446 OBDII: Evaporative Emissions (EVAP) system, vent control - Circuit malfunction
P0442 OBDII: Evaporative Emissions (EVAP) system - Small leak detected

With other treads out on Tacoma world I started to look at VSV valves. I learned that the two that are located in the engine bay are the VSV for PRESSURE SWITCHING VALVE & VSV for CANISTER CLOSED VALVE (CCV). The One that is located under the truck bed is the VSV for VAPOR PRESSURE SENSOR. This one is associated with the "charcoal canister" or "vapor canister" .


I started by looking in the engine bay because they VSV for the Canister and Pressure switch are easily accessible.

The above image is the location of the VSV for CANISTER CLOSED VALVE and VSV for PRESSURE SWITCHING VALVE both in the engine bay on the driver side.

I am pointing at the VSV FOR CANISTER CLOSED VALVE (CCV) and the VSV FOR PRESSURE SWITCHING VALVE is located just below. They are both mounted on the same bracket.

I loosened the 2 bolts holding the bracket to make it easier to get my multimeter probes on the pins. I ran the tests as described in the PDF attached. FSM PDF'S sourced from other Tacoma world threads. I attached them to this tread as well for quick reference.

My troubleshooting lead me to believe that the solenoids are functioning as they should. I have concluded that the VSV FOR CANISTER CLOSED VALVE and VSV FOR PRESSURE SWITCHING VALVE are not the issue in my situation.

NEXT it was time to remove my truck bed to access the "charcoal canister" or "vapor canister" . This went rather smoothly and I used the help of a buddy to move the bed off to the side so I could access the top of the gas tank.



With the bed out of the way you can see the vapor canister is attached to the frame and the extra rusty bits are the mounting brackets associated with this module.

The Blue plug was the next location to troubleshoot. VSV for VAPOR PRESSURE SENSOR.

This image shows what I believe to be the root cause of the error codes.
This broken connection is the smoking gun in my opinion and a reason pressure is leaking from my tank.
I did not bother testing the VSV for VAPOR PRESSURE SENSOR due to the nature of the busted part.

I looked briefly to see if the VSV for VAPOR PRESSURE SENSOR was available as a standalone part but did not have immediate success.

Due to the rusted nature of the bracket holding the vapor canister to my truck frame, I opted to buy the part/model from rock auto for $263. This parts looks like it should come with a new bracket and the VSV pressure sensor built into it.


I am planning to install this when it arrives and the biggest hurdle i foresee is freeing the bolts that go into the frame.



I will update when the part comes in but I am optimistic that this will fix the P0446 code and P0442 code.

 

If replacement of the canister doesn’t work, replacement of my rear O2 sensor fixed my P0446 code.

 

Any update to this OP??