2002 Audi A4 3.0 / A few weeks ago while stopped at a traffic light a "LOW OIL" warning popped up--- Checked oil, it's fine. Looked online to discover that there is a sensor on the latch for the HOOD and the hood has to be opened (and I guess closed as well) to have the warning removed.
Upon inspection of the situation I found that ONE of the wires from this sensor had corroded and broken off the sensor leaving no wire leading out of the sensor that could be spliced back. I was able to take a short wire and solder a NEEDLE to it, push it into the area where the wire had broken off and connect the other end to the wire leading to the sensor. This tricked the sensor into seeing the hood open, but this rig was not stable enough to be left in place to close the hood. However, the warning light did go away. But now I'm getting a battery drain. I've tested the broken wire leading to the sensor and it shows that it is HOT with the key off. So it doesn't make sense to me that a loose wire, not connected to anything would cause my battery to drain. Weird.

OK, long story, here's the question: Is it possible that this IS what could cause my battery to drain? The only other two things that have occurred prior has been that I briefly had the radio on with the key turned off. And I had a passenger in the rear back seat for about 5 minutes. Other that these that, nothing else has occurred that might be suspect. Car has always started fine during the two years I've driven it. The battery is the original battery. I'm stumped on this one.....

 

The wire may also be part of the anti-theft system. Based on my 2003 the system checks all doors, trunk, hood, and interior. I am not aware of any relationship between LOW OIL and a hood latch - makes no sense. More likely that when you stopped and either oil drained to normal level or pressure returned to normal range.