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amolin 08-31-2011 09:41 AM

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.

bendorfold 11-06-2011 03:12 AM

I'm suprised that there were no comments or replies to your post. My son just emailed me the link, he has this code on his 2001.

This is the best "How To" I've seen on a common problem. This is what it takes to be a mechanic, instead of just a "parts replacer".

The smoke machines I've used atomize vegetable oil and pump it through the lines. Very effective but expensive machines.

Thanks again for your work. We will be using it as a guide.

Georgie 11-06-2011 08:28 AM

The EVAP system monitor checks for fuel vapor leaks by performing either a pressure or vacuum test on the fuel system.

For 1996 through 1999 vehicles, the federal standard allows leaks up to the equivalent of a hole .040 inches in diameter in a fuel vapor hose or filler cap.

For 2000 and newer vehicles, the leakage rate has been reduced to the equivalent of a .020 in. diameter hole, which is almost invisible to the naked eye but can be detected by the OBD II system.

Finding these kinds of leaks can be very challenging. According to one expert, you can find a .040 in. leak with an ultrasonic leak detector but not a .020 in. leak. For such a small leak, you will need a smoke or dye-type detector.

Choices here include ultrasonic leak detectors that listen for sound waves produced by air or vapors escaping through an opening, smoke detectors that generate smoke which allows leaks to be spotted visually, and dye detectors that use a visible or ultraviolet dye to reveal leaks.

MarinaGG 09-09-2012 01:28 PM

Hello, I had the same error code P0442 on my 2001 Forester. Had a Smoke Machine Test done for $60 which detected a small leak in the Filler Neck. I got the filler neck from Advance Auto Parts for $117 and am having my mechanic install it. Let's just hope that works.

Javan 11-14-2012 06:56 AM

After over a year of putting up with the 442 code
I finally had my mech smoke test the system and sure enough, it's at the filler neck. Interestingly, since he did the test on Monday I now get the 457 code (loose gas cap), so I am thinking that during the testing, the hole got bigger.

I can not wait to have this resolved.....

JohnnyW 06-10-2014 06:13 PM

Interestingly enough I read this writeup about a year or so ago and thought, "How ingenious." Well, sure enough I now have a P0442.

First off, let me clear the air as I had one hell of a time finding anything called a CCV (valve). Of course searching google put me into a million hits pointing to Crank Case Ventilation valves, which we are obviously not talking about here. I did find info that identified the drain valve as the device I was after. It turns out that calling it a CCV valve is redundant as what you are really saying is Closed Canister Valve valve. I digress.

The sad fact is that I was unable to create any soap bubbles, at least that I could see. On a positive note, however, I was able to create a gasoline odor that using the old schnoz seemed to lead me to the old gas cap that everyone tried to throw on and hope the problem vanishes. Truth be told, I'm looking for just the o-ring for the original Subaru cap as that's what goes wrong with them, I like having the leash on my cap, and I can't see paying $XX.00 for a gas cap when it's a $2.00 O-ring that needs replacing.

So, I think the OP's writeup is a good one and worth it's weight in gold really, but you may have to get a little creative to get to the bottom of the issue. I sure hope an O-ring, or gas cap if there's no other way, solves my P0442. I'll post back with an update when I find out.

mekanic 06-22-2014 09:05 AM

I've used unlit propane gas to locate vacuum leaks - would that work for this?

blevrock 07-03-2014 09:32 AM

Has anyone had any luck with either the O-Ring replacement of a new filler neck? I'm getting the same error code. Has happened about 4 times now. Stealership has supposedly replaced and tightened some of the vacuum hoses and whatnot. I don't think that those have been inspected or replaced yet.

brackish 07-04-2014 07:36 AM

I'm there too....
Glad to reread the original post as I've got to take some action to deal with this code or, if not, take the vehicle out and shoot it. I have a 2007 LLbean which started having 0442 codes at about 55K coincidentally just after the dealer did a recall. The dealers representative insisted that they could not have caused it because they went nowhere with the recall that would impact the fuel system. The recall required the removal of the fuel pump so as usual, that stealership lied to me. And of course they refuse to take any responsibility.

This car has never been off road, I live in the south so it has never had the snow/salt cycle problem others have to live with. Last week at 84K I took it to a local mechanic who I trust to change the rear wheel bearings (another terrible Subaru design flaw) and asked him while he had it apart to do a smoke test. He did, twice, without charging me for either and could not detect a leak. So I'm back to the starting point, either resetting with my OBII reader every couple of hundred miles to be able to use my cruise control, or doing something about it. May try the air pressure soap bubbles method as described by the OP. Will be following all input to this subject to look for new directions to go. If there was just some way to override the cruise control disabling...........

TECH MOD 07-04-2014 09:01 AM

If he smoked it and didn't find it ,it could be the lines at the top of the tank or the fuel pump portal hatch. You lookin for .020 inch hole.

JohnnyW 07-04-2014 10:56 PM


Originally Posted by mekanic (Post 3645737)
I've used unlit propane gas to locate vacuum leaks - would that work for this?

I question whether it would of not. There's a valve by the charcoal canister that I believe opens to allow fuel vapors into the charcoal canister. Then there's another valve on the left (passenger) side of the engine up under the intake manifold that opens to allow vapors to come up from the canister, pass through the opened valve and be directed via another hose right into the intake manifold. In order for the propane thing to work you'd have to have a way of assuring one or both of those valves were actually being held opened by the ECU.

I'm working on another low dollar solution to this deal and I'll do a full write-up with pictures and the whole bit, "IF" I can make it pan out for me first. I don't want to go writing up a big thing only to find I've sent people in the wrong direction. :mob: Sadly I'll say that it'll probably take at least a couple weeks even if it does all pan out because I have a LOT of irons in the fire right now. So please, do wish me luck!

BA_from_GA 09-20-2014 09:51 AM

anyone have a pic of where the EVAP line routes into the intake manifold?

I'm getting a P0442 and am having a heck of a time tracking down the leak....Filler neck looks good, lines at EVAP Canister look good, top of fuel pump access looks good..... I'm at a dead end...

brackish 09-21-2014 01:20 PM

Exact same car, same year, LL Bean, same situation. Had it smoked twice, no one can find the problem. I thought I had it. Dealer did a recall that required the fuel pump to be removed and put it back with one of the studs not through the gasket hole. The stud was on the outside of the gasket. Replaced the gasket, properly torqued it in sequence. Obviously that was not it cause I'm still getting the 0442.

JTShaw 06-28-2015 10:01 AM

I might be a little bit late to the party, but I currently have this code on my '03 Forester XS. I also seem to having an issue being able to fill my tank. Did anyone else have this issue? After reading through the thread it's sounding like it's a filler neck problem, but I will definitely have to see if my dad can help me smoke the lines to see where the problem exists.

However - when it comes to gassing up - I have to find some magical way of holding the nozzle in order to make it fill without constantly stopping. I have only gotten lucky a couple of times in finding the sweet spot, otherwise I don't even bother filling my tank and I just put in as much as I can until I get fed up with fighting with it. Could these issues be related?

Dan9 06-29-2015 07:41 AM

Careful with that, I clogged my charcoal canister with fuel trying to force fill. You can try disconnecting 1 or the other small soft hoses on the fuel filler neck and see if you can gas up that way.

OP, great write up.

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