DCS light, loss of power in second gear

2001 Z3 3.0i (automatic). Was on the road today, and suddenly began experiencing, in second gear only (it's an automatic), a sudden loss of power and a blinking, then a steady DCS light. In first gear, no problem, no DCS light. I was close to home so I never took it to third gear. Where should I start?

Originally Posted by semarla

Where should I start?

Start by pulling the codes.

That many possibilities, huh? Don't have a code reader. What would be, say, the top three possibilities?

If you live in the United States, you can get the codes read for free at almost any auto parts store. There is no reason to just guess. I'm not sure if this is common elsewhere.

I assume you mean "DSC" or Dynamic Stability Control. The most common failure is a bad wheel speed sensor: the code will tell you which one. It can also be a bad controller, which is far more expensive.

I tried this at an Advance Auto Parts store. The guy came out to the parking lot with his code reader, but the Z3 plug in was not accessible. He was unable to get access to it. My closest BMW dealer in 25 miles away, and I'm afrain to drive the car that far with the power loss in second gear. Do you know anything about the location of the code plug-in on the Z3? What's needed to get access?

EDIT: Scratch my question. I looked online and it would appear the auto parts guy was looking in the wrong place. I'm leaving now to see if we can try it again in the right place.

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Okay. Update: I've had the code read. It's P0455, which apparently is an "emissions control leak," according to the reader. I have NO Check Engine light. Again, my problem is an intermittent (flashing, sometimes staying lite) DCS light accompanied by a power loss. I have a Service Engine Soon light that's been on for months (I know, bad me, but I haven't had the funds to deal with it), but NOT a Check Engine light. I should note that last fall, I had to buy a new gasoline tank cap because I lost the original. The cap is supposed to fit the Z3, but I'm not so certain it has a good seal. Shortly after that I got the Service Engine Soon light.

Ideas?

UPDATE TO THE UPDATE: I've researched online, and I'm now suspecting that the P0455 code is gas tank cap related, and has nothing to do with my DCS light and loss of power. Ideas?

Okay, here I have consolidated what I think I know so far: 2001 Z3 3.0i (automatic). Was on the road yesterday, and suddenly began experiencing a sudden loss of power and a blinking, then a steady DSC light.

I had the code read. It came up P0455, which apparently is an "emissions control leak," according to the reader. I have NO Check Engine light. I've researched some online, and I'm now suspecting that the P0455 code is gas tank cap related (I bought a replacement cap last fall, and right after that I got a Service Engine Soon light), and has nothing to do with my intermittent DSC light and loss of power.

So, I tried an experiment: Turned OFF DSC, and took it for a drive. I experienced a loss of power on a hill. I have NOT tried holding the DSC button down to get a "Brake" light. My understanding, I could be wrong, is that the DSC is not fully disabled unless you hold the button down for 3 seconds to get the BRAKE light on also. Is that true?

I'm assuming DSC exists for a good reason. Is it safe to drive with DSC completely disabled?

Any suggestions or ideas would be appreciated.

There has been discussions about what actually happens when you hold the DSC button down for 4-10 seconds. Some say it doesn't do anything some say it does. If you hold it down for a number of seconds and then release the button, the button is no longer active and if you press the button it will no longer turn the DSC back on. You must turn your car off to reset it. The next time you start your car the button works again. As far as "is it safe to drive without the DSC", DSC is a feature on newer cars. Older cars didn't even have it, so it is no less safe than driving an older car. Just be careful because your car won't try to save you from a slide when you have it off.