OB99W

What maintenance has been done recently? Specifically, when was the fuel filter last changed? Was the replacement O2 sensor an OEM unit? The trouble code may be misleading, anyway, because a sufficiently badly-running engine due to other problems can confuse things. By the way, have you looked at the fuel tank filler neck? They tend to rust out, and Evap system trouble codes don't always point to the actual cause. Check for bad lines while you're at it.

From http://www.ultimatesubaru.org/forum/showthread.php?t=29192&page=4 : From this thread: From this thread and http://www.ultimatesubaru.org/forum/showthread.php?t=29192&page=4 : If nothing else, USMB is "consistently" entertaining.

It's such a pleasure to have open-minded discussion of the possible causes of this problem, rather than anyone deciding that they have all the answers.

Nipper, the way I'm reading what you wrote, you seem to be saying that you think condensation is freezing in the interior (atmospheric pressure) side of the booster (please correct me if that's not what you mean). Obviously, that would require a certain level of humidity in the cabin air. As I've said previously, I've never experienced the "hard pedal" problem on my '99, which you thought might be related to the model year. But perhaps it might be related to personal habits, in least in some cases. I try to knock as much snow/ice off my shoes as practical before driving; I wonder if some people wind up with saturated floor mats because they don't bother, and/or have passengers contributing to that. The cabin air moisture might be elevated quite a bit that way.

In certain respects, some brake fluids designed for racing don't perform as well (especially long-term) as "standard" fluids. Since professional racers change brake fluid regularly, problems that occur with time aren't a big concern. If anyone is considering using a "racing" brake fluid for "street" use, I'd suggest reading the manufacturers info carefully first. By the way, if it's DOT-5 (silicone-based), forget it; DOT-5.1 (PAG), maybe.

Nipper has suggested that moisture freezing in the booster could be the problem, and I agreed with it being a possibility. Your experience would seem to support that. (Even with a "good" check valve, condensation might occur over time.) That got me thinking; I wonder if applying a vacuum pump (like the ones used to evacuate A/C systems) to the booster's vacuum line for long enough could reduce moisture sufficiently to eliminate the problem. I don't know off-hand how much vacuuum the booster can tolerate, but if nearly 30 or so inches Hg can be safely applied for about an hour, that should eliminate most of the moisture in the booster; normal engine vacuum can be as high as 28 inches Hg or so during rapid deceleration.

It's not a problem for the few seconds it would take to try what I suggested.

Ummm, you wouldn't have a transfer clutch or C duty solenoid problem, but you might have a viscous coupling one.

Nobody is guaranteeing anything, but did you read my post #4 in this thread and what I linked to in that post? The more "stuff" you throw at the problem and the longer you wait before asking a dealer or SoA about it, the lower your chance of getting Subaru to cover things is likely to be. If you don't mind my asking, why the reluctance to discuss this with Subaru? (I wouldn't want to have to use one of the smilies near the bottom of the window that opens when you click on "More". )

You're welcome; glad you liked the article. If it happens again, there's a way you can usually tell if it's the inhibitor switch: When you get the "click", don't release the key -- keep holding the ignition switch in the START position, and jiggle the shift lever with your other hand; if it begins to crank, even intermittently, it's probably a problem with the inhibitor switch. On the other hand, if that doesn't change anything, the cause is likely elsewhere.

Ooops, instead of "haven't been brought up" I meant to say "having been brought up". Maybe my brain fluid is too cold . I'll edit that post, because otherwise it's a bit confusing. I had a Pontiac Tempest which let water get into the parking brake cable sheath. I learned to not set the brake when it was below freezing (after getting stranded twice!), until I changed the cable out for a new one with better seals. My '99 is a little newer than yours, and it's usually about 10 deg colder here than where you are, but it hasn't had the problem discussed in this thread. It did fall into the range of VINs that had the master cylinders that were bad when cold, and it got a new one several years ago under the recall even though mine never exhibited that problem either.

Certainly to a significant degree. Possibly; isn't the full title "Lucas - Prince of Darkness"?

That seems prudent. IMO, certainly a possibility. My discussion of brake fluid was due to the topic having been brought up, not because I think it's the most likely culprit. As I said, DOT-3 and -4 disperse moisture, which makes a hard freeze at some point in the hydraulics unlikely at any reasonable temperature.

Sorry, Nipper, but this is correct. As I said in post #26 of this thread "full headlight current does indeed go through that switch and associated wiring". Perhaps if you or I were designing the circuit, the switch would just control power to relay coils, but Subaru didn't consult with us (well, certainly not with me).

Uncontaminated brake fluid will exhibit increased viscosity at lowered temperatures, but it shouldn't get to the point of causing hydraulic problems at temps typically seen in the US. DOT-3 or DOT-4 glycol-based brake fluids are "hygroscopic"; they absorb moisture (water) -- (DOT-5 type is silicone-based and has different characteristics). Rather than the water pooling in spots in the system, it should normally get dispersed in the fluid, making it tolerant of at least some water-contamination. It's recommended to flush brake fluid periodically, mostly due to concern over the moisture causing lowering of the boiling point of the fluid and possibly corrosion of hydraulic system parts. However, I suppose (I don't have specific info on this) it would be possible for the fluid to have a sufficient moisture content to make it more susceptible to problems at extremely low temperatures. Certainly if you typically drive through flooded areas or ford streams while off-roading, you should consider flushing the brake system periodically. Some people think that DOT-5 fluid would be better for their car, but it has its own drawbacks. While it isn't hygroscopic, any water that does get into the hydraulic system will not be dispersed in the fluid, but remain concentrated in certain areas; of course, it could then freeze or boil at those points. DOT-5 fluid also aerates (gets air bubbles in it) more readily than either -3 or -4, making for a less-firm pedal than most of us like. I'm not suggesting that the problem discussed in this thread either is or isn't a problem with the fluid or the master cylinder, and there may not even be a common cause. Under any circumstance, it would seem that it isn't something to be ignored, and the suggestion of reporting experiences to NHTSA is probably a good idea.

If your car meets the conditions given in the link below, by all means go to a dealer or call Subaru of America. You have little to loose, and may get the repair for free, or at least at a significant discount. Don't "cave in" easily; if they give you a hard time, tell them that even as a second owner you have the right to expect a certain level of quality in a Subaru, and that's why you bought one. It would probably help if you have proof of the original owner having previously done the proper thing. See: http://www.snedcs.com/dcsmain/service/WWP_subnet2-5-04.htm By the way, to meet the terms of the campaign, the "coolant conditioner" should be Subaru's own, and not some generic "stop leak".

I haven't looked at the wiring of more-recent models, but certainly the 90's models have the common hot power switched via relays while the steering-column-mounted switch controls whether the low or high beam connection is grounded; full headlight current does indeed go through that switch and associated wiring. In terms of the contacts, the relays take the brunt of the abuse when switching from parking to headlights (since the lo/hi switch remains stationary then), but the switch contacts take it when you flip to or flash the high beams. If I were trying to determine if voltage drop was a problem, I'd start with the high beams on and check for drop between the positive battery terminal and the headlights' common positive connection. If a significant drop is found, then it needs to be further tracked down; it could be in relay contacts, fuse block, connectors, the ignition switch, etc. If no significant drop is evident on the hot side, I'd next check for one from the negative battery terminal to the ground side of the headlight high beams, and then flip the switch to lows and check from the battery neg to the lows' grounds. A drop in the ground side could be due to contact resistance in the switch, connectors, poor chassis ground, etc.

That was primarily directed to the original poster, reeze, and anyone else not having a lot of experience, but it's still a good precaution even for long-time wrenchers. Burns from hot metal or battery acid should probably be avoided.

Another "this may be obvious" precaution: Be sure to disconnect a battery cable at the battery before removing the positive cable at the starter. Otherwise, unintended arc welding could be the least of your troubles. Unless you've ignored the safety precaution and yet managed to get this far, your ECU will have "forgotten" a few things, so the car may now start but not run as well as before (until you drive it a bit). That's normal, and after a few trips things should be fine again.

BTW, in that other thread you said: My response to that in the other thread was: "In the case of labored cranking and/or clicking from the solenoid, the problem could easily be a weak battery or poor battery cable connections." Based on your additional info, I'd start with checking the battery connections first and then move on to other things we've suggested.

In the case of labored cranking and/or clicking from the solenoid, the problem could easily be a weak battery or poor battery cable connections. If the problem is actually in the starter, in addition to the info given previously in this thread, the following might help: http://endwrench.com/images/pdfs/StarterServiceWin03.pdf

You're welcome. You posted that "previous message" in the thread I had linked to above. Speaking of that thread -- since your car has an auto trans, rather than having a starter interlock relay, it has an inhibitor switch controlled by the shift lever position (that's what RallyKeith was referring to). However, checking for 12V on the red/yellow wire at the solenoid when the ignition switch is in START position is valid with the auto trans as well. Here's an article that you might find useful: http://endwrench.com/images/pdfs/StarterServiceWin03.pdf

You might find some of the info in this thread interesting, although certain details refer to a manual-trans model: http://www.ultimatesubaru.org/forum/showthread.php?t=70369

At that mileage, you or someone else should at least visually inspect the springs for major rust or obvious defects. To check for sagging, verify proper ride height. If you don't have the spec for that, a local body or alignment shop might do you a favor and provide the measurements. Sagged springs lead to changes in suspension component angles, and that can lead to handling problems, so it's worthwhile checking if you're not replacing the springs. For the same reason, I don't recommend installing springs that lift or lower unless other things are corrected to accommodate the change.

Degrees F = (9/5 degrees C) + 32