Question about 2001 Toyota Corolla

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Hello my 2000 toyota echo's check engine light is on and it is reading error codes po440,po441,po446 I was told it is something with the emissions what is the problem

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The fsm covers all this, but no one reads books today,

too hard i guess.? to read official book by toyota.

it is on line, at and is $15 (DIY)

read it.

P04xx are not 02 like pam guessed, dead wrong.! sorry !

400s are mostly EGR and EVAP. never 02.

ill now do each, not guessing or speculating, only facts.

a tech, reads how each monitor is tested, (conducted) and

then reads what is expected during this tests.

called MONITORS.

the light is for smog sure, and 100s of other failures. if you scan the PCM , fully with a REAL scan tool , report all DTC errors not just some. or all answers wilL BE WRONG !

so usa car, just 3 DTC total. got you. covered.


EVAP Control System Large Leak (0.080") Detected
Top cause, fuel cap missing or loose or bad (cracked) or wrong type.

reset codes DTC with scan tool and drive ,got 400s'

if yes, you need to get the gas tank vents stem for air leaks.

called a pressure leak down tests. (ask) its not easy so.......

get it fixed?


EVAP System Incorrect Purge Flow Detected

same answer as 400s

446 (same system (tank fume vents) but more serious.

Evaporative Emission Control System Vent Control Malfunction
full FSM text to follow not BS like others post

Trouble Code Conditions:

When VSV for pressure switching valve is OFF, ECM judges that there is no continuity between vapor pressure sensor va­por pressure sensor and charcoal canister (2 trip detection logic) When VSV for pressure switching valve is OFF, ECM judges that there is no continuity between vapor pressure sensor and fuel tank (2 trip detection logic) After purge cut off operates, pressure in charcoal canister is maintained at atmospheric pressure (2 trip detection logic)

Possible Causes:

  • Open or short in vapor pressure sensor circuit

  • Vapor pressure sensor

  • Open or short in VSV circuit for EVAP

  • VSV for EVAP

  • Open or short in VSV circuit for vapor pressure sensor

  • VSV for vapor pressure sensor,dead or fibbing.

  • Charcoal canister cracked, hole or damaged

  • Fuel tank over fill check valve cracked or damaged

  • ECM (nah)

comments. (translated from ASE jargon to english)

vsv is vacuum solenoid valve.

this can mean the a real failure.

buy a new cap , reset DTC's and drive

if it comes back you need the system diagnosed.

there are lots of ways for EVAP to fail.

cap or just a simple leak or more complex.

ill not cover more complex.

you can login to and read the whole chapter on EVAP and learn all the tests, and solutions.

at any time.


P0446 Code Conditions (2-Trip Detection)
The PCM will set P0446 of one of the following conditions is detected:

  • With the VSV for the vapor pressure sensor off, the PCM detects that there is no continuity between the sensor and the canister.

  • With the VSV for the vapor pressure sensor on, the PCM detects that there is no continuity between the sensor and the fuel tank.

  • After purge cutoff is enabled, the pressure in the charcoal canister is maintained at atmospheric pressure.

Posted on Feb 11, 2015

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It's probably the 02 sensor (technically dealing with the exhaust) which will make it fail emissions. I have been told it may also be a dirty mass air flow sensor, which is located in the same housing as the air filter box. I am having the same problems myself, and the car is hesitating and has no power.

Posted on Aug 27, 2010

  • 1 more comment 
  • pamster918 Feb 10, 2015

    UPDATE: I forgot to come back and repost after my original comment above. I did buy a mass air flow sensor from a local Advanced Auto Parts for around $80 and replaced it myself by following a YouTube video! It was pretty easy, it worked, and I was so pleased with myself that I fixed the car! It was running fine afterwards with no hesitation, and I didn't have to pay a mechanic for labor! I still had to end up getting the 02 sensor replaced, but I found a mechanic who did the side job for me and saved me lots of money. No more problems passing emissions.

  • _-__-___-_
    _-__-___-_ Feb 11, 2015

    but your answer pam is dead wrong and your cars issues are not his, gue$$ing is expensive,

  • _-__-___-_
    _-__-___-_ Feb 11, 2015

    100% wrong system, totally, OP car has Fuel tank EVAP system errors.



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