Subaru Forester Owners Forum - View Single Post - ('03-'05) P0442 error code - SOLVED!
Thread: ('03-'05) P0442 error code - SOLVED!
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post #1 of (permalink) Old 08-31-2011, 09:41 AM Thread Starter
Forum Member
Join Date: Oct 2007
Posts: 11
Car Year: 2003
Car Model: Forester
Transmission: AT
P0442 error code - SOLVED!

My ’03 X started throwing emission leak codes about half a year ago. Initially it was “very small leak” code (0456 I think) that was not even stored but in pending state once in a while and I got it when scanned ECU for some other purposes. No check engine light back then. Some day, later, while driving I got check engine light on. There was p0442 code stored. I started gathering info about it, searching documentation and this forum primarily. Gas cap thing is easy to try but usually solves nothing I guess. I didn’t bother buying new one, just cleaned old one, WD40’d it a bit and got the same code few days later again. Obviously I began thinking about a way to test evap system for leaks. Smoke testing they call it. I don’t even know who does it around here and was reluctant finding them. I felt inclined to try solve issue myself. Warm summer night, single car in double car garage, plenty of space, bunch of various tools, family asleep, laptop with repair pdfs, cool beer cans.

I though I’ll describe what I’ve done and learned here to help somebody diagnose similar problems before wasting any money.
Looking at evap system diagram, I figured out that there is CCV valve to close the system and there is one of tubes coming to purge control solenoid valve (PCSV) easily accessible under the hood I could use to pump air into the system. Found some 12V DC wall adapter laying around and used it to activate CCV. CCV is located at passenger side, under rear fender, behind rear wheal. It has wire harness hanging down and easily accessible. PCSV is under passenger side intake manifold in engine compartment. It has one tube going to the manifold next to it and the other heading to the back of the car. I unplugged later one from PCSV and extended with some 10ft tube of appropriate diameter I happened to have around. That allowed me to be close to right end of the car while blowing air into it with my mouth.

Right after it I began to hear hissing sound above rear-right wheel and smell gasoline vapors. Next step was to take off plastic shield covering fuel tank filler neck (FN) to get better access to eval tubes under it. Obviously, all bolts holding it were rusted badly. I broke some of them, others were not going anywhere so I had to cut plastic around them to get it free. As it was said, rust, dirt, salt etc falling from above. Then I stole my wife’s plant spraying bottle, added some shampoo to it and sprayed it all around pipes and tubes in there while blowing air into the system. Eventually nice soap bubbles appear around little square box sitting on top of FN close to the top end of it. It’s called shut-off valve (SOV) on diagram. I believe the same thing is called rollover valve sometimes here. Not sure why. Anyways, the thing is leaking at the point it touches the FN. I believe rust ate up some metal there and made it loose.

Next step is to pull FN out, get SOV off and look into it. Broke three rusted bolts under filler cap. Unscrewed one holding the middle of FN to car body. Disconnected evap hoses connecting FN to metal pipes on the body. Underneath the car, I disconnected FN from large rubber tube going to fuel tank. Note here, there was less then half of fuel in the tank. Nothing spilled out when I disconnected the FN. Be careful if you got more fuel left.

I got FN out, without even taking the wheel off, just jacked it up a bit higher. Using wire brush and some sand paper got rush off it. As much as I could. It looked not too bad. Rusty yes but plenty of metal left. After 8 salty Canadian winters. There was no way to unscrew bolts holding SOV to FN, so I just broke them and drilled new holes though what ever left there. Blowing air though one of connector and closing the other holes I found where it is leaking. Apparently SOV consists of two parts, square box and flat plate joined with use of 4 rivets. Two opposite sides of box, extends a bit and touch flat plate on sides. Like |[]|. With help of pliers I bend them away a bit to widen the gap. There is rubber gasket underneath sealing gap between two parts of SOV. I cleaned a bit around with knife and put 5min epoxy in the gap, small amount, like inch stripe on each side to cover gasket from outside.

Finally, painted whole thing with rust primer and two coat of rust paint, drying a half day in between. Installed all back after. I used 2 new bolts to attach SOV to the FN and 2 more to attach top of FN to the car. I greased bolts liberally, hoping it will keep rust away.
Overall work time is about 2 hours excluding drying time. Practically no bucks spent, granted that you have plenty of little things laying in your garage.

I spent another few days driving around, about 300km total, before got Evaporation system check status “completed” finally without check engine light on. Seems like mission accomplished.

Not decided about plastic filler cover. To put it back, drill some holes in it, or just apply thick coat of something on the filler tube to protect from salt and debris.

Last edited by amolin; 11-11-2011 at 09:27 PM.
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