Fails emissions with fault code p0446.. how do i fix this?

P0446 Evaporative Emission Control System Vent Control Circuit Malfunction. The code P0446 is set when the engine computer recognizes a fault or restriction at the vent control part of the Evaporative emission control system (EVAP).

https://www.obd-codes.com/p0446

code p0446 refers to evaporative emission (EVAP) system-vent control-circuit malfunction===causes --wiring--EVAP canister purge valve--ECM
code p0455 refers to EVAP system-large leak detected===causes --hose connections--intake leak--EVAP canister---EVap canister purge valve
code p0172 refers to system too rich, bank 1===causes intake blocked---EVAP canister purge valve--fuel pressure ---EGR system---injector/s ---ECM
because the EVAP purge valve appears in all codes I would be inclined to change that unit first the run the fault codes again

P0446 Evaporative Emission Control System Vent Control Circuit Malfunction The code P0446 is set when the engine computer recognizes a fault or restriction at the vent control part of the Evaporative emission control system (EVAP). The description of the fault varies between different car manufacturers, but one thing is common, the code P0446 doesn't directly point to a defective part; some testing might be required to pinpoint the faulty component. What can cause the code P0446: - faulty vent control valve - blockage at the vent hose, vent filter or vent control valve - open or short in the vent control valve circuit - bad charcoal canister - EVAP system leak - faulty EVAP system pressure sensor - bad vacuum switching valve (VSV) - stuck open purge valve (solenoid)

-I hate to say that but absolutely NO. If you don't know much about car. All these codes are emission code.
P0068 Mean Throttle position sensor.
P0171 Mean system too lean.
P0446 Mean evaporator emission control system has not correct flow
P0507 Mean Idle air control is too hight.
P0116 Mean engine coolant temperature.

Need to have a mechanic to check one by one to determine which part is effect before replace it.

Good luck

Mai Lor

The definition of fault code P0446 is the carbon canister ventilation function failure, this problem does not affect driving performance of engine driven, but due to the fault will cause ECU to trigger fault light, we also should handle. Especially in the automotive emission control is being paid more and more attention today, we should master the principles of automobile emissions control system and diagnosis method of repair, the repair of the vehicle can keep the original vehicle emission control function.
source: obd2 tools auto scanner key programmer

Hi there:

A code P0446 could mean one or more of the following has happened:
- Faulty vent valve
- Open, short or excessive resistance on Vent valve control circuit
- Blockage of vent valve
- Bad PCM




With a P0446 OBD-II trouble code, here are some things to try:
- Replace Vent valve
- Repair open, short, or resistance problem in control circuit
- Repair open, or short, or resistance problem in power circuit

- Replace PCM




Hope this helps.

P0446....Evaporative Emission Control System Vent Control Circuit

you have a fault with the vapour control ,could just be a pipe perished or loose somewhere along the line

Code P0446 is related to your vehicles evaporative emissions system. Often this is caused by your gas cap not being properly tightened.

Before running out and spending money on this issue be sure the gas cap is in good condition and make sure it's tight. (At least 2 or 3 turns after it begins to click)

Drive the car for a few days. If the check engine light doesn't turn off you will need to go to a repair shop who can scan and troubleshoot the problem.

Good luck.

where is Evap Emission Control System Purge Flow fault

These codes are all for the Evaporative Emissions System.

P0440- Evaporative emissions system fault- just saying there's something wrong with the system.

P0441- Evaporative emissions system- Incorrect purge flow- saying that the system isn't purging the raw fuel vapors (hydrocarbons- HC) as well as it should.

P0446- Evaporative emissions system- Control valve circuit low- there is a valve, usually located on the charcoal canister at the rear of the vehicle, that opens to allow fresh air to enter the evaporative emissions system as the engine vacuum purges the fuel vapors from the charcoal canister and closes when purge is not needed to prevent leakage of those fuel vapors to the atmosphere (HC is a greenhouse gas and is regulated as such by the fed gov't).

Given that you have the incorrect purge flow code and the control valve code together, my bet is that the vent control valve has failed (causing the P0446) and is not opening to allow fresh air into the system to displace the air from within the system that is being pulled to the engine. Since you have no fresh air entering the system, the engine will pull a vacuum on the system instead of the vapors "flowing" into the engine (causing the P0441).


I hope that this is helpful to you!!!


ASE Master Technician with L1 and X1 Certifications; Nissan Scope Technician; Chrysler Level 3 Silver Technician- 12+ years experience.