I brought my 2001 A6 with 160k to a local garage to have it inspected, so I could see if it was worth reparing/keeping. As a part of the inspection, the garage put a dye into my oil that after 100 miles. After I drive 100 miles, I'm supposed to come back and see where oil is leaking from. Before the dye was introduced, the garage needed to degrease my engine so that the dyed oil would stand out after the requisite 100 miles of driving.

Well, when I went to the garage, I had no Air Bag warning light. When I went to pick-up car, the Air Bag warning light was on.

I took the car back today after driving maybe 10 miles, so the shop could see if they messed anything up during the inspection or degreasing. The shop says they did nothing wrong, and that they pulled code 00588 - resistance too high. They say they can chase down the code further for $99. What do you think?