Red triangle with exclamation point came on and sometimes engine falls to idle

Run a diagnostic test to see the codes to find out what parts are causing the light to come on.

Sounds like the engine didn't want to restart like it should when the battery went low. Have a garage check codes.

I recently purchased a 2005 Z4 (76,000 miles), and I just experienced the same thing (beep, then yellow Brake and Triangle Light (w/exclamation point/semicircle appears on dashboard). It is intermittent. Did you ever find a solution?

Look in your owners manual

Can also find those symbols on the internet

My 2003 warning light frequently goes on after going down a long hill. The dealer has tested, and thinks that it is related to the traction battery being overcharged or overheated after a long hill. Doesn't seem to affect performance and the the problem clears up after turning the car on and off several times. If you have no power when you accellerate, it suggests that the electric motor has cut out some how, until the problem is cleared up. Would be interested in finding out what your solution was.

try installing a new brake light switch ref. haynes repair manual for vw 98 - 2002.

The new sensor has to be programmed. You probably need a scanner that can communicate with that system. Check for related trouble codes.

Hi, The exclamation point in triangle blinking is the "Emergency Blinker" This blinker turns on all all of the turn signal lamps at all four corners of the car. Left and Right, Front and Back. The triangle represents the European symbol for roadside emergencies. In fact on European Mercedes and other cars there is a triangle shaped reflector you can put behind the car so that other drivers know you have an emergency. THAT TRIANGLE ON YOUR DASHBOARD IS A BUTTON. PUSH IT ONCE. THE BLINKING SHOULD STOP. If you have a roadside emergency, and are broken down by the side of the rode. Push the Red Triangle and your lights will blink on and off ouTside to say, in effect "help".
Hope this helps.
Best,
Mark

I have a yellow triangle with a ? on my dash what does this mean

The light you're referring to isn't a check engine light, the check engine light merely says "check engine" in orange and is on the lower right hand side of your instrument panel. It is reserved for telling you that something annoying is happening with your engine, but is usually related to a bad sensor reading in your emissions control system.

That other light, (the exclamation point in the red triangle, in the center of the instrument panel,) indicates that something very bad is happening with your engine, it only comes on if continued driving could severely damage the engine. I highly recommend against driving it at all, as doing so will probably just make your problems worse.

What's your temperature gauge reading? If it's going really high, or remaining pegged at the bottom, you may have some kind of coolant system issue, and the motor is shutting down due to an overheat. (Which can then result in a blown head gasket, which I have done...)

I have experienced this twice: once due to a coolant line blowing and overheating my engine, and once due to a major oil leak. (Oil running straight out of the bottom as soon as I put it in. Yikes!) Neither of these problems is something you want to drive your car with until you have discovered the source of, and rectified; the problem. Check all of your fluids and oil, watch all of your gauges, and see if anything out of the ordinary is going on.

If you can't see any obvious reason for this, take it in to the shop, because your car is trying to protect your engine, and getting an estimate is a lot cheaper than replacing your engine.

Good luck,

-R