P0446 evap vent control

[Starjammir]

Hey all,
I am stuck on this code. I replaced the purge valve under the truck thinking it was a bad valve. Any other suggestions?
50k on it.
I also have a CEL for a 02 sensor bank one, which by scanning shows no voltage so I'm guessing a bad sensor.
Truck also has some missing too. Threw the random misfire code at me.
Truck has been missing thought all gears. I replaced the DPFE sensor about 20k ago.

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[RangerBill]

Hey all,
I am stuck on this code. I replaced the purge valve under the truck thinking it was a bad valve. Any other suggestions?
50k on it.
I also have a CEL for a 02 sensor bank one, which by scanning shows no voltage so I'm guessing a bad sensor.
Truck also has some missing too. Threw the random misfire code at me.
Truck has been missing thought all gears. I replaced the DPFE sensor about 20k ago.

I believe that code is not referring to the purge valve. It refers to the canister vent valve. It is the second from the top in the electrical diagram.

From the shop manual:
P0446 - EVAP System Vent Control Circuit

Description:	This DTC sets when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified EVAP canister vent valve duty cycle by PCM command.
Possible Causes:	VPWR circuit open KAPWR circuit open CANV circuit open CANV circuit short to ground CANV circuit short to voltage CANV circuit short to KAPWR Damaged EVAP canister vent valve
Diagnostic Aids:	To verify normal function, monitor the EVAP canister vent valve signal PID EVAPCV and the signal voltage (PCM control side). With the valve open, EVAPCV indicates 0% duty cycle and a voltage approximately equal to battery voltage. When the valve is commanded fully closed, EVAPCV indicates 100% duty cycle, and a minimum voltage drop of 4 volts is normal.

 

[Starjammir]

I'm sorry I meant canister valve. The one you referred to that's the one I replaced.

 

[RangerBill]

I'm sorry I meant canister valve. The one you referred to that's the one I replaced.

Did you clear the code after replacing the vent valve and did the code return?

 

[Starjammir]

Yup, returned after a 10 minute drive.

 

[airline tech]

It needs a wiring check, or you can possibly (Pull and Inspect for Corrosion) on the following connectors.
To properly check its easier with a High-End Scan Tool with Bi-Directional Control
But can be done (Old School) with a Meter.
Note: C408 is a known problem connector for (Moisture & Water) intrusion and the contacts get corroded.

Ref: The Following Connector Pinouts for wire checks:

Let's Check for Voltage:
NOTE: Power Checks are with Key On Engine Off (KOEO)
Ensure Key is OFF - when you disconnect any connector and then turn the key back on to perform the checks

Canister Vent Connector disconnected
Meter: (Voltage)
Note: Pinout for C450 (Canister Vent Valve)
Pin #1 - VPWR - Green
Pin #2 - PCM Control (Ground) - (CANV)= Green / Blue

Note: Pin # To Ground = Red Meter Lead to Connector Pin and Negative Meter Lead to Body Ground (Frame) a good clean ground

Disconnect C450 (Evap Vent Valve Connector)
Pin #1 to Ground = Battery Voltage
(Yes) stop here, and we need to check the PCM output control of the valve (Pin #2)
(No) Proceed to next step

Disconnect C410 and Measure (Upstream) Side - Inspect for corrosion or pushed pins
Pin # 12 to Ground = Battery Voltage
(Yes) - Wire issue between C410 & C450
(No) - Proceed to next step

Disconnect C408 and Measure (Upstream Side) - Inspect for corrosion or pushed pins
Pin # 4 to Ground = Battery Voltage
(Yes) - Wire issue between C408 & C410
(No) - Wire issue Upstream of C408, need to dive deeper and check Splice (S123)

For the PCM Output Control (Ground) (CANV)
Have all 3 connectors disconnected
and Measure (Ohms Scale)

C450 Pin #2 to C410 (Fuel Tank Side) Pin #11 = 3 Ohms or Less
C410 (Harness Side) to C408 (Downstream) Side Pin # 5 = 3 Ohms or Less

If both voltage and Ohm checks are good, then we need to dive deeper for Voltage (S123) or Ohm checks (Disconnect the PCM Connector) and meter between:
C175B Pin #22 to C408 (Upstream Side) Pin # 5 = 3 Ohms or less

Splice (S123) is located in the driver's footwell just after the harness comes into the cab (Firewall) is the general location, will have to open harness to locate it.

Again: This is much simpler with a Bi-Direction Scan Tool that can command the Vent Valve Open and Closed and a full check the EVAP System as EVAP Codes can be misleading in T-Shooting such as bad vent tube on the fuel tank, clogged canister, bad EVAP Purge valve and or any leak in the system, and the misleading part is the fact that you have a code P0446 (driving) you in the wrong direction.
But however, the wiring checks I have posted boils down to a small part of the system and it involves checking a (KNOWN) connector that absorbs moisture.

The most common failure parts are:
Canister Purge Valve (On the Engine)
Vent Tube Assembly (That runs along the top of the fuel tank)

 

[Dereku]

Should still be under warranty as an emissions component. 8 years or 80k miles.

 

[harringtondav]

Should still be under warranty as an emissions component. 8 years or 80k miles.

So I thought when I went to the dealer for the same issue. Nope. But my ESP picked up most of the cost.

 

[harringtondav]

The EVAP purge valve could be bad or have a bad connection. I had the same code and the dealer replaced it. .....didn't help, so they looked closer and found a bad wire back at the canister vent valve.

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