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P0455 Howto change the Canister Vent Solenoid

Discussion in '1994-2004 V6 Mustang Tech' started by systemloc, May 19, 2011.

  1. systemloc

    systemloc New Member

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    On my 2000 3.8L V6 Mustang, I got a P0445 "Evaporative Emission Control System Leak Detected (gross leak)". The only symptom of a problem was an occasional smell of gas while cruising (more than 30 mph, no acceleration).

    The Evaporative Emission Control System is designed to catch gas vapor from the tank and burn it, rather than allow it to vent to the atmosphere. While the car is off, the fuel tank is vented through a charcoal canister, then a solenoid valve. When the computer detects that the car is running, in drive, moving greater than 30 mph, and at minimal acceleration, it will perform some system tests, closing off the canister vent solenoid, so the canister and fuel tank are no longer vented, then it opens a second canister purge solenoid to connect the fuel tank and canister to the intake manifold. It then closes off both solenoids and monitors the vacuum in the fuel tank via a sensor mounted on the top of the tank. If the vacuum doesn't hold, it throws one of a few leak codes. The faster the vacuum falls, the larger the leak code.

    The following only applies to the 3.8L V6, as the V8 has all the parts in different locations.

    The canister is located under the rear driver's side bumper, behind the rear wheel, above the exhaust pipe, next to the fuel tank. The Canister Vent Solenoid is mounted on the canister toward the rear of the car. The Canister Purge Solenoid is mounted in the front passenger side wheel-well, under the large protective plastic above the tire. The system is connected to the intake manifold on the passenger side just on the engine side of the throttle body. The service port is on the passenger side next to the A/C condenser.

    So, anyway, I found that this code means there's a vacuum leak somewhere in the system. I was told the most common cause of a leak is the seal around the gas cap. Check it for cracks, and try replacing it. Most people recommended buying a dealership gas cap, as some aftermarket caps may not seal correctly.

    I also read that it is very rare to have cracks or leaks in the hoses themselves.

    So, I changed my gas cap with no luck, and all the hoses looked good. I found on a different forum, someone had a similar problem and it was actually the plastic flange connecting the fill hose to the tank.

    At this point, I took it to a mechanic and had them smoke the system. One shop wanted $60, but I found one that did it free with some other work for me. The idea is to fill the system with smoke and look to see where it comes out. Part of that procedure was putting a probe wire onto the Canister Vent Solenoid to make it close, sealing the system, otherwise smoke would just blow out the vent, and taking off the gas cap to initially fill the system with smoke. At this point, smoke began to pour out of the Canister Vent Solenoid under the driver side rear quarter panel.

    That part is $92 at the dealer, or $72 at Napa. On inspecting the old part, it has a rubber boot that was obviously cracked. I had already replaced it, but if anyone else has the problem, try to buy just that rubber boot. I'm sure it'd be much cheaper!

    More info

    [​IMG]
    Item Part Number Description
    1 9F980 Evaporative emission test port
    2 9C915 Evaporative emission canister purge valve
    3 9F945 Canister vent solenoid
    4 9D653 Evaporative emission canister
    5 9C047 Fuel vapor control valve tube assembly
    mustang throwing Charcol canister code, help! - Mustang Forums at StangNet

    [​IMG]
    This is the Canister Vent Solenoid, located under the driver-side rear bumper.

    [​IMG]
    Here's the rubber boot off. The rubber boot creates a vacuum seal.

    [​IMG]
    The culprit! You can see the crack in the boot.

    [​IMG]
    You can see the part installed here, above the exhaust pipe.

    [​IMG]
    To remove the electrical plug (green arrow), there is a tab that you hold pushed in as you pull it off. Note, you push it in, not pull it out, as some other tabs are. The part has a bracket to hold it in place. The bracket is mounted to a metal tab (red arrow). I carefully slid the plastic off of the metal piece. This took a good deal of force and finesse. The plastic looked fragile, and I was worried that it would break, so be careful! Finally, the part is attached to the canister. It just pulls straight out with little trouble.




    Here’s what some of the error codes mean:
    P0440 Evaporative Emission Control System Malfunction
    P0441 Evaporative Emission Control System, Incorrect Purge Flow
    P0442 Evaporative Emission Control System Leak Detected (Small Leak)
    P0443 Evaporative Emission Control System Purge Control Valve Circuit Malfunction
    P0444 Evaporative Emission Control System Purge Control Valve Circuit Open
    P0445 Evaporative Emission Control System Purge Control Valve Circuit Shorted
    P0446 Evaporative Emission Control System Vent Control Malfunction
    P0447 Evaporative Emission Control System Vent Control Circuit Open
    P0448 Evaporative Emission Control System Vent Control Circuit Shorted
    P0449 Evaporative Emission Control System Vent Valve/Solenoid Circuit
    P0450 Evaporative Emission Control System Pressure Sensor Malfunction
    P0451 Evaporative Emission Control System Pressure Sensor/Switch Range/Performance
    P0452 Evaporative Emission Control System Pressure Sensor/Switch Low Input
    P0453 Evaporative Emission Control System Pressure Sensor/Switch High Input
    P0454 Evaporative Emission Control System Pressure Sensor/Switch Intermittent
    P0455 Evaporative Emission Control System Leak Detected (gross Leak)
    P0456 Evaporative Emission Control System Leak Detected (Very Small Leak)
    P0457 Evaporative Emission Control System Leak Detected (fuel cap … off)
     
  2. macuser27

    macuser27 Active Member

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    Nice write up! I have a 2003 with P0442 code. Been wanting to smoke test it, but all the quotes I got were ridiculously high ($180-200).
     
  3. systemloc

    systemloc New Member

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    That's way higher than anyone told me. Check your gas cap seal for cracks, the hose to the intake manifold, the canister, and that rubber cover. You might try reseating the hoses too. Failing that, you might inspect the purge valve too. I've seen it, but didn't take pics. It doesn't have any rubber cover or anything that might wear out.

    P0442 is a small leak, so your looking for something small, like a tiny crack, or a hose that needs wiggling.

    If you don't see anything, call around to local shops. It should cost less than $100. When I smoked mine, it really didn't put out a ton of smoke, so you may have difficulty seeing the smoke out of a small leak. Look closely!
     
  4. Greg687

    Greg687 Member

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    related to this, what do you think would be causing pressure to build up in the gas tank? I get the "evaporative purge malfunction" code as well but I get pressure building that releases when I take the cap off. Do you think a new cap would fix the CEL?