Eng. Fault code PO446 Evap. System need Help.

[BACKNBLACK]

Originally Posted by BKLYNH2

I would appreciate any help I could get with this.
I have had an engine warning light for a while now with several codes and have replace several components.

I am down to one code left.
PO 446 the scanner says evap system control fault.

What is this and can anyone explain what needs to be done to correct it?

Make sure your gas cap is screwed on tight. This is most likely the cause of the code. Evap is not likely an issue in this vehicle unless you had a supercharger or evap port clog. Did you get gas and overflow the tank? Also a possibility. In any case evap can only be tested from an OBD scanner and pass when it is COLD.

[HUMTECH]

A loose gas cap will set a p0455, evap system large leak detected

[IRA51]

yes I know a PO446 is a evap code haveig to do with the canister path being blocked or restricted ,and a purge selenoid valve is often time the culprit or a bad hose or pinched or blocked hose ,all I saw was your post with a PO445 my bad .

Originally Posted by HUMTECH

A loose gas cap will set a p0455, evap system large leak detected

[Yetti]

I have one thing to add. I live in Michigan and its very "moist" here. the same code had appeared on mine 3 times in 5 years. I just cleared it and it stayed gone for a long time. it seemed to set if we had a huge change in temp or humidity. being as the tech guy is in AZ. and the Problem is NY. I believe that is lost in translation. I tend to wonder if the NY guy is fighting the moisture issue I was having. seemed to set if I had less then 1/2 tank when the temp changed.

[IRA51]

I would look at the gas cap first . than if after you replace the gas cap and drive it for 3 or 4 drive cycles if the MIL light won't go out check all evap hose's and the canister .

[HUMTECH]

See above, P0455 is a code that will set with a loose cap, P0446 is an evap restriction. Not trying to be a prick, but each code has its own diagnosis and i do work on these on a daily basis.

[HUMTECH]

DTC P0446

This DTC tests the Evaporative Emission (EVAP) System for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid valve Open and the EVAP canister vent solenoid valve Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, this DTC sets.
The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent solenoid valves.
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