2007 X3 3.0si 4wd / DSC / ABS light ON

Hello,
I've recently bought a used 2007 BMW X3 3.0si with 45,000mi. Car is in excellent condition; however, I'd just noticed the 4WD/DSC & ABS light popping up frequently. I've been researching around and it appears there are a couple of possible causes. I have not had the car officially diagnosed yet, but would just like to verify a couple things on the forum from members w/ experience on this issue. I guess my main concern is, will this affect the way the car drives and the efficiency of the AWD x-drive power transfer system? A member had mentioned that when this light pops up, the AWD system is handicapped and will run mostly as a RWD. I have a feeling this is directly affecting the fuel economy of my car because I'd noticed that the gas mileage on my X3 is really bad compared to its factory specifications. I think it averaged as low as 15mpg.

***I'm planning to drive it like this for a short time before bringing it in for service because I'm a little tight on cash right now.

I don't know if this was among the possibilities that you researched, but before you get into any high-dollar repairs (like transfer case, etc.), you should have your battery checked. A 2007 with relatively low mileage like that one probably will still have the original BMW battery -- which may not have been kept properly charged if the vehicle sat in the garage for lengthy periods, and only got driven short distances. That's bad for the long-term life of the battery, and this trio of lights often signals (though not by design by BMW) that your battery may be on its last legs.

As far as the mileage goes, it could be as simple as needing to reset the average mileage in your OBC. This should really be done every time you fill the tank in order to get an accurate reading of the MPG; otherwise, it just keeps averaging and averaging until it reaches a mean value that won't change no matter how well you drive. Although granted, 15 MPG is pretty low for a 2007, even in pure city driving...

Originally Posted by beyondx4

Hello,
I've recently bought a used 2007 BMW X3 3.0si with 45,000mi. Car is in excellent condition; however, I'd just noticed the 4WD/DSC & ABS light popping up frequently. .

How are the tires? Same size, same tread depth?

Originally Posted by beyondx4

.... I have not had the car officially diagnosed yet, ....

Drop by any BMW dealer, hand them your key, and let them them tell you the service history.

Odds are that a previous owner had it in sometime for that very problem.

No point in paying again to learn the same thing.

Hopefully you are just the second owner. If you are the 3rd. or 4th., chances of an easy resolution might be more remote.

A long-term mpg average of around 15 is really poor.
That must be intensive stop and start city driving exclusively which would be consistent with a battery in a low state of charge.

My long-term average is 10.4L/100km. (22.6 mpg (U.S.) or 27.2 mpg (Imp.)),
and as already mentioned, the 2007+ models are more fuel efficient than the earlier ones.
But I do use mine as fast town-to-city transport, not for short errands.

Thanks alot for the ideas. Just yesterday, I took the X3 out and had a little family trip to the Aquarium, which totaled about 180 miles on the highway; however, when I filled up the tank this morning, it took 14 gallons to fill up, which is ridiculous because that equals <13mpg. I have a friend that works on BMW and he will pop in his dx machine to get me the error codes and find out which sensor is emitting this error this weekend. I'll see if I can get to BMW to have them pull out the service records (I hope they will not charge me for this). My tires are pretty good (stock 235/55/17). It appears my X3's battery may be weak, because the other day, I forgot the interior lights for just a couple hours, and the next thing I know, it won't start. Then I took out my good remote jumper and attempted to start it; again it did not work. I then had to remove the battery and plugged it into a slow charger and charged it overnight. As of right now, it is starting fine, but I will go out the car tonight when I get home to check the actual battery voltage back there. May I ask, what is the reason why a weak battery causes the fuel economy of a car to go down like that? I was under the impression that when the engine is running, the alternator would be able to kick in, keeping a 14.4v output. This startles me because my 180 mi trip was mostly on the highway and I'm getting less than 13mpg!

Originally Posted by beyondx4

... May I ask, what is the reason why a weak battery causes the fuel economy of a car to go down like that? I was under the impression that when the engine is running, the alternator would be able to kick in, keeping a 14.4v output. This startles me because my 180 mi trip was mostly on the highway and I'm getting less than 13mpg!

There's probably no connection between a weak battery and your poor gas mileage; I'd look for another source for that problem, if further investigation reveals that one exists. Poor gas mileage can result from a number of sources. But I agree with you: 13 MPG highway on a 2007 X3 is WAAAY too low... What kind of engine RPM's are you seeing at highway speed? Is this an automatic or a manual transmission?

Assuming your charging system is working properly, your assumption there is correct. But if the battery won't hold a charge, even a good alternator can do nothing...

In fact, if the battery fails altogether, the car will eventually die on the road. The electrical system is powered by the battery; when all the components of the charging system (battery, alternator, wiring, etc.) are functioning properly, this is largely transparent to you, since as the battery is depleted by electrical draw, the alternator replenishes the battery. When the battery is failing (i.e., won't hold a proper charge), the electrical draw hasn't changed, but the battery can't supply the demand (even with the alternator trying to keep it charged). When the battery fails altogether (i.e., will no longer hold a charge), whatever charge is left in the battery will be depleted by normal operation of the vehicle, and then the vehicle will stop running -- even with the alternator functioning perfectly.

Thanks for the explanation. I was trying to kind of make sense of the weak battery somehow triggering the 4WD warning light, and in turn shuts off the X-drive system, causing the car to run in a super inefficient mode. My RPM looks normal and there are no unusual engine shaking or sounds. In fact, it is incredibly smooth and powerful (my first BMW). I usually drive the car under the Automatic mode and sometimes switch over to the Manual mode for a little fun.

My 05 only averages 15-16 mpg but I drive all city

I'd just came back from my BMW buddy and his diagnosis scan revealed there is a problem with the TRANSFER CASE. Now I'm not sure if it's the "Transfer Case Actuator" or the actual "Transfer Case", but I'll have to drop it off to my buddy for him to do a thorough check on the car to see what is the real problem. That could be the reason why the car wasted so much gas, even more on the highway. Gosh...I'm so sad.

Originally Posted by beyondx4

..... I forgot the interior lights for just a couple hours, and the next thing I know, it won't start. Then I took out my good remote jumper and attempted to start it; again it did not work.

I thought if interior lights are left on, the sleep circuitry comes into play after about 20 mins. to turn them off.

Doesn't apply if the lights are on because a door is left open AFAIK, especially for the hatch.

But in any case, a healthy battery should be able handle interior lights on for quite a number of hours (a lot more than 2) before failing to start the car.

BMW Service Advisors apparently like to tell owners with failed batteries that they do not drive their vehicles enough.
This can get misinterpreted by those who drive every day in slow and heavy traffic to their school or job 5 miles away, and take evening and weekend trips to the nearby golf course, corner store, etc.
What the S.A. should be saying is that the battery only gets sufficiently recharged on trips of at least 10 miles (say) at moderate to high speed.

Does sound like a new battery is needed which may solve the warning light issue and leave the poor m.p.g. problem to be examined in isolation.

UPDATE: Just seen the post above. Haven't heard of transfer case problems causing poor m.pg., just noises. Hope this isn't a 3rd. separate problem.