P0446 Evaporative Emission Control System Vent Control Malfunction
 

Wanted to start a fresh thread for this issue for any future inquires.

1998 ES300 with 308k miles.

I'm reading the Service Manual for troubleshooting the code and trying to understand all the components involved.

The last two photos show the VSV for EVAP connector that had a broken tab which I replaced with a new one connector (white)

Attached PDFs of the Service Manual for:
1. P0441/P0446 troubleshooting
2. Charcoal Canister Inspection
3. EVAP Parts Location


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Broken VSV for EVAP connector
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New VSV for EVAP connector

from my experience, this is your charcoal canister that will need to be replaced

Are there tests I can perform on the canister to see if it’s bad? What are common symptoms of a bad canister?

I found a vacuum and compressed air canister port check and I heard if it rattles it’s bad. Should be receiving the MityVac hand pump soon to test it.

I found a lot of threads about the charcoal canister under P0446 but most of those posts also has P0441 and P0440 at the same time. Mine is only P0446.


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Mine was only p0446

We found out it was the canister by performing a smoke test. I think one of hoses/plastic pieces was cracked.

Looks like rockauto has the canister for your for $360

Mine is a 2002 Es300

I'll try the smoke test as well when I remove it for inspection. That price is actually higher than Lexus OE, I've been seeing $250-$300 at online dealers.

I already pulled off all the big vacuum hoses from the EVAP system and they're all looking rough and crusty. Small cracks around the edges, one of them just crumbled into pieces.

Removed the charcoal canister for testing. Checked all ports with a vacuum hand pump and canned air - results are inconclusive. Not sure how much vacuum or air flow it’s supposed to have while testing. Did the shake test and it sounds like sand moving around in a bottle. Don’t know if that constitutes a rattle. So long story short I bit the bullet and ordered a new canister, would like to run the same tests on the new one to compare. :)

Also removed all EVAP related hoses, most of them are cracked and or broken from disassembly but some were already cracked prior to removal. Replacements have been ordered and the ones that cannot be ordered from the dealer have been measured for custom fitment.


Valve Set EVAP VSV Short Inlet Hose

7/32”” ID x 1/2” OD

5.5mm ID x 12.5mm OD

Nipple size: 6.35mm


Valve Set EVAP VSV Short Outlet Hose

7/32” ID x 3/8” OD

5.5mm ID x 9.5mm OD

Nipple size: 6.35mm



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Thanks for the measurements. Those custom molded hoses don't hold up, even in the cooler climate here they get baked and fail.

The document attached from your first post - Charcoal Canister Inspection provides the psi & vacuum figures along with which ports to cap & testing sequence. Or I might be mis-reading your question.
0.26 psi - yes that's correct, less than one psi
1.01 in.Hg - vacuum

Also I attached SF doc (for '97)to test the following

1. INSPECT VSV FOR EVAP
   (See page SF–52)
   
2. REINSTALL VSV FOR EVAP
   
3. REMOVE VSV FOR VAPOR PRESSURE SENSOR
   
4. INSPECT VSV FOR VAPOR PRESSURE SENSOR
   (See page SF–56)
   
5. REINSTALL VSV FOR VAPOR PRESSURE SENSOR
   
6. INSPECT VAPOR PRESSURE SENSOR
   (See page SF–58)

Thank you, I think I wasn’t reading carefully when I was testing. I believe I got 0 vacuum on the gauge. The compressed air being less than 1 psi is something I’m not sure how to measure, does that mean that if I feel any air coming out then it passes that test?

I did make sure to block off the ports are specified.

You can take an old hose, attach to the port(s) being tested and blow through it where it calls for compressed air. The series of tests for the canister are testing the diaphragms/check valves.
Example (page 846)

• While holding port B and port D closed, blow air (1.76 kPa, 18 gf/cm2, 0.26 psi) into port A and check that air does not flow from port C.

If it does comes out of port C, in this test, the canister check value is bad

Retested the canister following your recommendation. All the ports tested okay.

Received new canister and the results are identical. The only difference is the new canister doesn’t have “a loose sand rattle” like the old one.

All the hoses definitely needed to be replaced, so I feel good about taking everything apart and testing/inspecting. Once I finish the reassembly, I’ll test the EVAP VSV and Vapor Pressure Sensor if issue comes back.