OB99W

By the way, there was a recall for bad O2 sensors on certain 2000 model year Subarus. It wasn't specifically for heater trouble, but it might be worthwhile contacting a dealer or SoA and see what they'll do (at no charge ).

I just looked at the wiring diagrams for the '99 OB/Legacy and '01 Forester (I don't have the '00 OB/Legacy one handy), and the O2 sensor heaters (front and rear) are fed via a set of contacts in the main relay; it's therefore possible that it or related wiring/connections could cause a problem triggering the P1133 code.

Porcupine73 has a good point; since the Subaru P1133 code doesn't indicate a particular sensor, it may well be a heater circuit problem but not at the sensor itself.

The P113x codes are usually for front O2 sensor problems. The P1133 code therefore probably indicates the front sensor (or wiring/connection) is where the problem is. If a new front sensor is needed, it's usually best to get an OEM one, since it's the one that's critical to how the ECU adjusts the air/fuel mixture. EDIT: It seems P1133 doesn't necessarily indicate a heater problem restricted to the front sensor; see following posts in this thread.

When the engine is started "cold", the ECU runs "open loop"; that is, the engine gets fed a predetermined rich fuel mixture. Once the oxygen sensor is hot enough, it provides a signal that allows the ECU to adjust the mixture (it runs "closed loop"). The exhaust stream can heat the oxygen sensor to operating temperature, but that typically takes a few minutes; in order to help minimize exhaust emissions, front oxygen sensors often incorporate an electrical heater to warm the sensor faster. If the heater isn't working correctly, your car will waste some gas and pollute more than it should for a few minutes after each cold start. Once the sensor gets hot due to the exhaust, operation should be normal, even if the heater isn't working. So, it's unlikely that your car will be hurt due to this problem. At worst, besides the slight additional fuel usage, there might be a lttle bit of fuel dilution of the engine oil. Still, I'd suggest taking care of the problem when you can afford to.

Anyone needing specific code info might want to try this Innova/Equus page: http://www.iequus.com/support/obd2_definitions.php Just make sure to look for the particular make.

Many throwout bearings are self-aligning/self-centering; even if they appear to be "off" before installation, they align correctly when in use.

Yes, it's possible for only the ISO-9141 operation to be faulty. You may have checked for this already, but make sure that none of the pins are bent and that the connector is being fully inserted; sometimes they're a bit tight and don't make good contact without a little "convincing". If you can easily get to the back of the DLC in the car, make sure all of it's pins are latched into the connector body. Otherwise, if it's not something simple like a blown fuse or connector trouble on the Subaru, then it could be a problem with the ECU (but I wouldn't jump to that conclusion yet).

Take a close look -- it's not just the axles!

The radiator fans are switched by relays controlled by the ECU, based on data such as coolant temperature and other factors (such as whether the A/C is turned on).

Not likely; there's a one-way clutch mechanism in the starter that allows the engine to turn faster than the starter is driving it. It's more likely that the overruning clutch could be damaged than would the teeth on the flywheel.

Yes, that's typical behavior with the test mode connectors attached. Leave them disconnected. If the scanner was ISO-9141 compatible and working properly, adding KWP2000 compatibility shouldn't have changed things; if it did, I'd suggest asking Harrison R&D what's going on. Not offhand, but the DLC (Diagnostic Link Connector) definitely is fused, usually along with other things on the same circuit.

You shouldn't have to couple the green test mode connectors to do an OBDII scan. Assuming the Harrison scanner incorporates the proper communication protocol, I'd check for a possibly blown fuse in the Subaru.

That wouldn't be typical of torque bind. As others have said, look elsewhere.

Right; a good diagnostician assumes nothing, and isn't led down a possibly wrong path by information from a customer, patient, client (or forum member ). Yes, unfortunately even after several shops declared it free of leaks.

Okay, so 65 and below doesn't reveal a problem, but 75 or so does, and your gas mileage is good, but slightly down... The problem is obviously very subtle. The things that are typically different with a change from 65 to 75 MPH cruising are additional demand for fuel/air/spark, and an increase in heat and exhaust gases that the engine has to rid itself of. You previously mentioned the possibility of low fuel pressure; that, or ability to deliver sufficient volume could be an explanation, and cylinder #3 may just be more sensitive. Since you've already replaced the filter, the pump itself could be suspect. As WAWalker has mentioned, you may indeed have some valve issues. Another possibility (and I admit this is going a bit "out on a limb") is a slight exhaust restriction. That can cause high-speed-only miss and some gas mileage reduction, but usually wouldn't be limited to just one cylinder. Two more questions: 1) Do you see any difference in the temperature gauge reading when cruising at 75 versus 65? 2) Could you try loading the engine more on a trip at 65 MPH (turn on headlights, etc.), and see if that will turn on the CEL at the lower speed?

That's why I asked about the amount of fluid needed. Obviously, normal brake friction material wear eventually requires adding fluid at the master's reservoir to offset that going to the wheel hydraulics. Assuming there are no external leaks or a leak into the booster, if driving conditions don't explain things (for example, mountains eat brakes) it's possible that some accelerated wear is occurring due to the brakes not releasing fully when the pedal isn't being depressed. Also, some brake friction material just wears very rapidly.

How much fluid are you having to add each time? http://www.abcauto.com/MessageCenterDetail.aspx?ContentID=13

Yep. When the ECU senses that the engine speed should be relatively constant (no significant changes from the throttle position sensor, etc.), it "assumes" that each pulse from the sensor will occur at a specific time. Because a misfire will slightly slow the engine for an instant, the ECU determines that one has occured if a pulse from the sensor is "late". A characteristic of this monitoring approach is that any problem resulting in momentary slowing of the engine will be interpreted as a misfire; that means ignition, fuel, or valving problems all look the same to the ECU. One of the difficulties in trying to diagnose the problem is that "the car runs fine and won't throw a code with around town driving or on short (slower speed )trips. Only when cruising at 75-80 on the highway after about 1-1.5 hrs will it come on.". The ECU needs sufficient time with a warmed engine running at a constant speed/throttle to determine misfire, especially if the trouble is intermittent. So it may be that if the "around town" trips are very short, don't allow for full warmup, rarely include constant speed (lots of stop-and-go), etc., an intermittent problem may actually be occuring during local driving, but not be detected. Highway cruising, on the other hand, is ideal for the ECU to "see" such a problem. If we assume the misfire is indeed only occuring at highway speeds, then certain possibilities come to mind. I don't have the time to get into that right now, but I do have a couple of questions: 1) Does it actually take "cruising at 75-80" (not at 60, for example) for the CEL to be set? 2) Just how great is the "great mileage"; in particular, what's the local versus highway mileage you're getting, if you can separate the two?

Great! Thanks for getting back to us with the outcome.

Normal charging causes a certain amount of electrolysis (the dissociation of the hydrogen and oxygen in the electrolyte). Overcharging increases electrolysis, elevating the temperature somewhat, but under normal circumstances to nowhere near the boiling point; the bubbles seen are mainly those of hydrogen and oxygen gas, not water vapor. Vigorous bubbling will cause venting of electrolyte. Obviously, overcharging isn't good, and charging voltage should be checked to verify that it isn't excessive. (EDIT: Gel and AGM type batteries don't outgas with normal charging, in case anyone was wondering.) If the charging system is okay, it's more likely that the battery is suffering from sulfation. It's normal for lead sulfate to form on the battery plates as the battery discharges. However, sometimes that sulfate forms hard crystals that normal charging won't reconvert; with sufficient sulfation, the battery voltage rises more rapidly than normal during charging, and there will tend to be more venting than usual.

Not that Nipper needs defending , but he did say the bulbs are "affordable" at RS.

While Duty Solenoid C controls fluid pressure to the clutch pack, it isn't the only thing that can affect it. Take a look at these to get an idea of how the AWD works: http://main.experiencetherave.com:80...er_system1.jpg http://main.experiencetherave.com:80...er_system2.jpg http://main.experiencetherave.com:80...er_system3.jpg If the ATF hasn't been changed recently, it might be due, and a full flush (with ATF, not additional chemicals) could help. Also, some early '90s 4EATs had a filter added in a trans cooler line; if the filter has never been replaced, it may be partially obstructed and somewhat reducing line pressure. (However, it's likely that low line pressure would show up in more than just slow engagement of AWD.)

You may find this thread interesting: http://www.ultimatesubaru.org/forum/showthread.php?t=19805 Also, this, especially page 13: http://endwrench.com/pdf/feb2004pdf/4EAT.pdf

Take a look at this: http://www.ultimatesubaru.org/forum/showthread.php?t=80437