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Dan
Dan, Technician
Category: Toyota
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Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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My 2001 toyota sienna has a code P0420 & a P0446 . no symptoms

Resolved Question:

My 2001 toyota sienna has a code P0420 & a P0446 . no symptoms , I replaced front converter and I am looking for the location of the vapor pressure sensor on car but cannot find . haynes repair manuals. shows this car has a vps (vapor pressure sensor) behind the fuel tank , any help is appreciated . Thanks .
Submitted: 4 years ago via ChiltonDIY.
Category: Toyota
Expert:  Dan replied 4 years ago.
Did you install a OEM converter or aftermarket?
Customer: replied 4 years ago.
I installed OEM Toyota parts .
Expert:  Dan replied 4 years ago.

Ok, thats good. Toyota did put out a computer update to take care of this problem to modify the values so this code isnt set when there isnt actually a problem. When the converter isnt the problem it is usually the oxygen sensor. As far as the P0446 that usually means the Evap canister has failed but could mean other things. Verify that the 3-way Vacuum Switching Valve (VSV) on the canister operates correctly. When the VSV is not grounded, the Fuel Tank Pressure (FTP) sensor should be connected to the canister side of the system only. When the VSV is grounded, the FTP sensor should monitor only the fuel tank. Monitor the FTP sensor, unplug the 3-way VSV, draw vacuum into the canister and verify that it will hold vacuum, and the FTP voltage will decrease.
Test and verify that the purge solenoid and wire harness are all OK. The purge solenoid should apply vacuum to the charcoal canister when grounded. Also verify that the hose from the purge solenoid to the charcoal canister does not leak. Let me know if you have questions, thanks.

 

P0446 EVAP Vent Control Solenoid Circuit Malfunction - With Automatic Transmission

Possible CausesSetting Conditions
  • Charcoal canister is clogged, loaded with fuel or with moisture
  • Fuel tank over-fill check valve cracked or damaged
  • Fuel tank seal leaking, fuel tank cracked, damaged or leaking
  • Fuel vapor hoses/tubes blocked or restricted, or fuel vapor control valve tube or fuel vapor vent valve assembly blocked
  • Vacuum hose or tubing cracked, damaged or disconnected
  • Vapor pressure sensor has failed
  • VSV circuit for the canister purge is open, shorted to ground or to voltage
  • VSV for the CCV is open, shorted to ground or shorted to voltage
  • VSV for the pressure switching valve is open, shorted to ground or to voltage
  • VSV for vapor pressure sensor circuit is open, shorted to ground or to voltage
  • Vapor pressure sensor has failed

P0420 Catalyst Efficiency Below Normal (Bank 1) - With Automatic Transmission

Possible CausesSetting Conditions
  • Catalytic converter has failed (check for physical damage and discoloration)
  • Check for air leaks in the Air Induction system (e.g., in the intake manifold)
  • Check for air leaks in the exhaust manifold and in the exhaust pipes
  • Front HO2S or rear HO2S is contaminated with fuel or moisture
  • Front HO2S or the rear HO2S is loose in its mounting hole
  • Front HO2S is older (aged) than the rear HO2S (HO2S is lazy)

Customer: replied 4 years ago.
There is no three way valve VSV . There is a two way valve with a two wire connector , and there is no vapor pressure sensor on the cannister.All the vsv switches checked good.,except cannot find the vapor pressure sensor.Maybe 2001 TOYOTA DON'T HAVE VPS
Expert:  Dan replied 4 years ago.

The vapor pressure sensor is on the fuel pump and the VSV is located on the canister.

 

graphic

Customer: replied 4 years ago.
I checked the VSV on the cannister but I still don't see the vapor pressure sensor on the diagram , the fuel pump assembly contains a fuel pressure regulator but no vapor pressure sensor.
Expert:  Dan replied 4 years ago.

Here is a picture, let me know if you have more questions. Thanks

 

graphic

Customer: replied 4 years ago.
I see the VPS in the diagram now ,I was mislead by a service manual ,i will test the VPS & will get back to you for more help . Thanks alot
Expert:  Dan replied 4 years ago.
Sounds good, let me know how it goes or if you have more questions. Thanks
Dan, Technician
Category: Toyota
Satisfied Customers: 21473
Experience: Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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