I replaced evap vent solenoid & dtc came back

Question edited for clarity, 'evac' to 'EVAP' and toss in some CAPS.
Question moved to model category.

Better to test it than just replace. $30 on Amazon, $90 at Autozone.

https://www.google.com/search?q=2001+ford+f150+code+p1451


The P1451 code indicates that there's an issue with your vehicle's EVAP systems vent solenoid. The engine control module (ECM) looks for a change in the EVAP system pressures to validate that the EVAP vent solenoid has actually opened or closed the vent.

p1451 Code - Evap Emission Control Sys Vent Control Valve ...

Kelley Blue Book https://www.kbb.com > obd-ii > p1451
Replacement

https://www.google.com/search?q=2001+ford+f150+evap+systems+vent+solenoid+replacement

..

there are like 1billion cars noW doing this.

1. the gas cap was loose or bad !!!
2. theN the driver did not know it takes 30 driving cycles to clear the CEL lamp. OOPS 30? OBD2 DOES THAT. PER SERVICE MANUAL RULES, IF YOU READ THEM.
3. the fuse did not blow, or you'd have not asked where it is, I get that.!

99% of the time the cap was just loose or bad
my car the 1% time, the purge solenoid stuck
and my walmart silicon spray'd there (INSIDE IT) ended FAILURE for 50,000 more miles.
learn to buy AND USE a scan tool (borrow, rent ,buy)
tighten the cap again
scan the pCM see the cel lamp reasons./
push reset on the toll (CEL goes off if lucky and not 100 other DTC errors set)
and drive 3 times or more and the CEL stays off.

the other resets are(NO SCAN TOOL,. REALLY?)
1: PULL BATTERY LUG FOR 15MIN AND PUT BACK
OOPS RADIO GOES DEAD. dang
2: PULL ALL IOD FUSES. THE PCM MEMORY FUSE ONLY.
Ecm F29 IS IT(MEM) (PCM) 10AMPS
ALL DTCS NOW GONE, STORED. THE DATA FELL; INTO THE BIT BUCKET AS THEY SAY

IF ALL TESTS AND WILD GUESSING REPLACING ALL EVAP; VALVES. THEN COMES THE SMOKE MACHINE TESTS.
TO FIND THE LEAK
THIS IS AND EPA MANDATED MONITOR IN USA.
FOR SURE. THE 2 FUSES FOR BOTH EVAP VALVES ARE HERE.

B1S1 is bank 1 sensor 1 Should be the O2 sensor on the very front of the engine right behind the radiator.

just part of the emission system .
Wells EVAP Training with Sgt Tech P0440 P0441 P0442 etc

DTC P0446 Evaporative Emission (EVAP) Vent System Performance
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 Open and the EVAP canister vent solenoid 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 Closed and the EVAP canister vent solenoid 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.

Location should be back by the fuel tank.

first off, the P1447 DTC is triggered when the EVAP control system isn't operating properly or there is a leak between the intake manifold and the pressure sensor. the parts between the pressure sensor and intake manifold are:

1. EVAP canister purge control solenoid valve
2. EVAP canister purge control valve
3. EVAP canister purge volume control valve (Part # 14930-3M201) YOU WILL HAVE TO DOUBLE CHECK ON THE PART NUMBER WITH THE DEALER FOR THE PRICE.

If you've received this P1447 DTC, chances are that the brick of charcoal in the canister has fallen apart over time, and filled the lines with charcoal. this affects parts 2 & 3 from the above list, and of course the EVAP canister (Part # 14950-1s717 $144.22). but when you replace the canister, you have to replace the EVAP canister vent control valve (part # 14935-54u06 about $100), and don't forget the o-ring (part # 16618-40u00 about $1.60) that goes between the canister and the vent control valve.

If you attack this DTC early enough, all you have to replace is the canister and vent control valve with the o-ring, which will add up to under $300 MSRP...a lot better than paying upwards of $1000 for parts and labor. Don't be scared to do it, it's actually quite simple.

D

DTC P0446: Evaporative Emissions (EVAP) Vent System Performance
Circuit/System Description
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 inch H2O in a calibrated time, this DTC sets.
Diagnostic Aids
?€¢
An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP canister vent solenoid valve inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.

?€¢
An EVAP canister, vent hose, or vent solenoid valve that has restricted flow may cause this DTC to set. Using a purge solenoid command with a scan tool will allow vacuum to be applied to the system instead of pressure. With the engine running, the EVAP canister vent solenoid valve open, and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than 5 inches H2O.

?€¢
An EVAP canister filter that is restricted can cause this DTC to set. Refer to Evaporative Emission Canister Replacement .

?€¢
Disconnecting one component at a time while the EVAP system is under flow will help to pinpoint a restriction in the system

Do you have a scan tool that reads data PID'S ?
Your FTP - fuel tank pressure sensor could be at fault !

Ignition ON and fuel cap removed, verify that the FTP sensor parameter is between 1.3-1.7 volts. ?‡'
If not within the specified range, go to the FTP sensor section in Circuit/System Testing.

1. Install the fuel cap.
2. With the engine running, the EVAP canister vent solenoid valve open, and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than 12 inches H2O.

?‡'
If the fuel tank vacuum is greater than the specified range, go to the restriction section in Circuit/System Testing.

If

P0446 has nothing to do with the canistor !
DTC P0446 Evaporative Emission (EVAP) Vent System Performance
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.
DTC P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage


How to troubleshoot an EVAP Pressure Sensor problem P0452 GM

EVAP Vent Solenoid Code P0446 The solenoid is stuck open !

Trouble Code: P0446

Evaporative Emissions (EVAP) Vent System Performance

Possible Causes:


The EVAP system tests run when the engine is first started and meets the Conditions for Running the DTC. An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP canister vent inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill condition.An EVAP canister, vent hose, or vent solenoid valve that has restricted flow may cause this DTC to set. Using a purge solenoid command with a scan tool will allow vacuum to be applied to the system instead of pressure. With the engine running, the EVAP canister vent solenoid valve open and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than 5 inches H2O.An EVAP canister filter that is restricted can cause this DTC to set. Refer to Evaporative Emission (EVAP) Canister Filter Replacement and Evaporative Emission (EVAP) System Cleaning .Disconnecting one component at a time while the EVAP system is under flow will help to pinpoint a restriction in the system.Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.For intermittent conditions, refer to Intermittent Conditions .

There has been a service bulletin isued for that code. I have run into this before, also the wires comming out of the connector. That would bethe first thing to check. Here is what the bulletin states. Emissions - SES Lamp ON/DTC P0440 (EVAP) SetNotesFile In Section: 06 - Engine/Propulsion SystemBulletin No.: 02-06-04-044Date: August, 2002TECHNICALSubject: Service Engine Soon (SES) Light Illuminated, DTC P0440 Set (Replace Fuel Tank Evaporative Emissions Control System (EVAP) Vent Solenoid Harness) Models: 2000-2002 Chevrolet Cavalier2000-2002 Pontiac Sunfire ConditionSome customers may comment that the SES light is/was illuminated.A technician may find DTC P0440 is stored in the PCM.CauseThe EVAP solenoid harness may be misrouted around the rear antilock brake (ABS) wire harness causing a chaff/damage to the EVAP vent solenoid harness, setting DTC P0440.CorrectionFollow the service procedure below to diagnose and correct this condition.1. Install a Tech 2 scan tool and select the appropriate vehicle. Verify that a DTC P0440 is stored in the PCM. 2. Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle in General Information (SI Document ID # XXXXX).



Locate and inspect the EVAP vent solenoid harness (3) routing. The harness may be routed below the ABS wiring harness (4) at the right rear corner of the fuel tank, causing stress on the EVAP solenoid harness (3).





4.Disconnect the EVAP vent solenoid harness (3) from the EVAP vent solenoid (2) and connector C313 (1). Discard the EVAP vent solenoid harness (3).

5.Connect the new EVAP vent solenoid harness (3), P/N 22687059, to the EVAP vent solenoid (2), route the harness above the rear ABS harness (4) and connect the EVAP vent solenoid harness (3) to connector C313 (1).

6.Lower the vehicle.

7.Clear the DTC's with the Tech 2 scan tool.

If all of the wires are good you will want to check for any leaks in the evap system.

Hope helps.

DTC P0446 Evaporative Emission (EVAP) Vent System Performance

The vehicle control module (VCM) monitors the performance of the evaporative emission (EVAP) system by applying a predetermined level of vacuum to the EVAP system and monitors the vacuum decay rate. The VCM sets this diagnostic trouble code (DTC) if the vacuum decay rate is more than a predetermined value. The VCM monitors the amount of vacuum and the amount of pressure in the EVAP system by monitoring the fuel tank pressure sensor. For this DTC, the VCM turns ON both the EVAP purge valve and the EVAP vent valve when the Conditions for Running the DTC are met. This applies an engine vacuum to a closed EVAP system. The VCM turns OFF both the EVAP purge valve and the EVAP vent valve when the system reaches a correct amount of vacuum. The EVAP system should quickly RELEASE the vacuum in the EVAP system with the EVAP purge valve OFF and the EVAP vent valve OFF (open). This test indicates a blocked or restricted EVAP vent path if the EVAP system fails to release the vacuum quickly enough.