Multiple codes showing-PO420,440,441,446. (Oxy sensor,3way cat.malfunct. evap syst.malfunct.,charcoal can, VPS, incorrect purge flow) Seems the vapor pressure sensor is involved on PO441 & 446? Also, some type of incorrect purge flow? I am driving an '01 Toyota Sienna. I replaced the gas cap & (aftermarket) c.converter last yr.. Am told that I missed a svc.bulletin on some computer module which would affect this system. Anyone, got a fix for this problem? I can probably handle the "hands-on" side of this, even manual diagnostics, but I am unsure how to begin to troubleshoot this. I am thinking to purchase a vps & charcoal can. Any advice will be greatly appreciated!!!
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Re: Emission Control Systems Malfunction
Charcoal cannister is listed on the first 3 codes so changing it would be a good idea. The last code P0446 indicates broken vacuum line or VPS so it looks like you have a good handle on it. If you can rule out any vacuum leaks, then the charcoal cannister and VPS should cure your problem. Best of luck.
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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)
Here is the description: Evaporative Emission Control System Purge Control Valve circuit malfunction... The purge valve for the Evap. system (the charcoal canister and associated hoses- keeps gas fumes from tank from escaping into the air) has a circuit malfunction. Find the purge control valve and check its wiring. It should be close by the canister, but sometimes a remote location.
P0441 = Evaporative Emission Control System Incorrect Purge Flow. Trouble Area(s) Open or short in VSV circuit for VAP. Open or short in VSV circuit for vapor pressure sensor. Open or short in vapor pressure sensor. VSV for EVAP. VSV for vapor pressure sensor. Vapor pressure sensor. Vacuum hose cracks, holed blocked, damaged or disconnected. Charcoal canister cracked, holed or damaged. P0450 = Evaporative Emission Control System Pressure Sensor Malfunction. Trouble Area(s) Open or short in vapor pressure sensor circuit. Vapor pressure sensor. ECM.
EVAP Emission Control System - Small Leak Detected (1.0 mm). This code can be set when 1. fuel filler cap is not completely tight, 2. when various hoses get punctured or the canister close valve does not seal completely, 3. there is an actual leak in the charcoal canister, fuel tank, or other EVAP system component, 4. if any one of these components are malfunction (a), fuel tank pressure sensor, (b) purge control solenoid valve, (c) canister close valve, or (d) fuel cap. An engine vacuum leak would not set this code, Usaly there is a sensor on fuel tank called Evap controll switch that has failed