S90 P0442 Suggestions On What To Check Next?

[mattskav]

So I've got a 1998 S90 throwing consistent P0442 - Evap Small Leak

The gas cap gasket looks fine. I checked the lines to and from the canister all the way up to the purge and vent valves. I took both purge and vent valves off and blew through them with 12V applied and not and both seem to be working fine with no leak. The fuse is also fine. The only thing I found was the supply line to the purge valve had severe wear from rubbing against the intake manifold but the line was still sound (I thought I had found the issue).

So I have no Idea what's going on. The only other thing I can think to do is to tear apart the wheel well and check the filler but when I gas it there is no smell.

I guess I could plug the vent line and bypass the purge valve and listen for a leak but is that safe to do or will I implode the gas tank? That would be decidedly un-awesome.

Any other suggestions? Anyone know a way to force the system to do a evap test?

Matt

[mattskav]

Well anyway thanks for all the helpful suggestions

Here is the way to diagnose this problem for anyone else, this applies to a P0442 Evaporative emissions leak (small leak) on a 1998 S90 and probably every other car on the planet. It's listed in order of probability to find the issue on the S90 and I tried to order it in terms of the ease of finding the issue.

First inspect/go buy a new gas gap and reset the light to make sure that's not the issue ($9 at NAPA)

If that does not work check the EVAP lines starting at the rear of the car and work forward
1. In the trunk pull back the bottom liner nearest the seat to the left side of the car to get access to the fuel pump / sending unit plate
2. Remove the square plate (10mm bolts X 4)
3. Check all of the lines in there ***note this is where my issue was, the coupler on a vent line from the rear of the car was split*** Some people go crazy fixing this stuff, I just cut the coupler above the split and jammed it back on.
4. Check the tubes at front of the car, the vent solenoid is on the driver side mounted near/at the firewall and the vaccum solenoid is drivers side mounted near the fender mid engine bay (near/above an EGR solenoid) look for cracks in the coupers or lines (NOTE **although not broken in my car the line FEEDING the vaccum solenoid from the manifold Tee had been in contact withthe manifold and was 9/10ths the way worn through and this may be your issue)
5. Jack the car up real high and make it safe to get under there (10 to 20 jack stands minimum)
6. Check the tubes at the carbon canister (UNLIKE a FWD there was no J type tube that was broken here) Note that the green lines are actual gas supply / return if those have a hole you have a different issue entirely.
7.If none of this works (i.e. you can't find a break in a hose) go back to the engine bay and pull the vaccum solenoid out. Again this is the one on the drivers side in the middle of the bay mounted near the fender. It is the smaller valve and is **not** the one with the tube going over to the air pump. This valve is normally closed and opens to run the EVAP check. Clean off the couplings 'cuz your gonna stick your mouth on them. YOU SHOULD NOT BE ABLE TO BLOW THROUGH IT AT ALL. Apply 12 volts across to the pins you should hear a click and when you blow through it should open up.
8. Ok if that wasn't it then the almost final step is to work on the vent solenoid. This is normally open and closes to do the leak test. You can't get this one out of the car easily so don't even try. Instead you will see a large ~1" diameter dump tube out of the bottom of the valve going into the frame. Pull that tube out of the frame and bend it up to your pie hole. Clean it up good because it's probably gross and you are going to stick it in your mouth. It should be open to start but mine was hard to blow into anyway don't freak out about that. This would be a good time for a beer. YOU MUST apply 12V to test this one unlike the other valve. Apply 12V, I used leads from a volt meter to do this and a battery from my kids power wheels and this worked REALLY slick. This should close ther valve and you should not be able to blow through it at all. If you can, that's the issue.

If either step 7 or 8 failed replace whatever valve failed.

If none of these things worked the only other thing I can think to do is check everything again and then pull the wheel and wheel liner and look at the fill tube and vent tube up there but this probably isn't easy to do. I didn't do it, so no promises on if you can even see it.

Other than that; take it in.

[mattskav]

One final update, the code came back on after fixing the connection between the gas tank and the steel tube that passes into the trunk well. I tore the whole vehicle apart. The access to the filler tube is not in the wheel well as I thought; you actually get to the whole mess by taking out the driver side left trunk carpet liner. The issue wasn't there though however if you have tried everything else I recommend taking this apart because there is an epoxy connection in there that could leak.

For me it turns out there was a second split/cracked tube that connects a 3-way vacuum tee to the gas tank itself. To get to this one you have to look through the same trunk access hole way to the right center of the tank and really wedge your hand in there to get at it. This one was not as easy to fix as the other there is a 2.5" long slightly angled rubber connector that connects the hose to the tank and it had big split in it. It really needs a new OEM part or a trip to the hardware store...

[oldschoolvolvo]

glad you found out the source of the problem. i'd recommend getting the oem hose. i had a similar issue and just used hardware store hose which deteriorated in a few months and i needed to do the job over again w/ the right hose.