I have a 99 a4 Quattro 1.8t tiptronic with the transmission not shifting stuck in limp mode. I got under the car and started looking around and found trans fluid covering most of the underside and a hole in the driver's side of the transmission just under the engine oil filter. I took some pictures of the hole from underneath and through the driver's side wheel well a gear can be seen through the hole.

What should be there?

Is this were the trans fluid is coming from?

Also, I have a v-checker pro from ECS tuning and found codes:

00297 Speed sensor malfunction

00597 Differing wheel speed impulse

Are all of these things related?

From what I have been able to find it seems as though the G68 sensor is what is missing but am not sure and could not find a definitive picture or part number of that sensor for the 99 a4 Quattro.

I bought this car cheap a few weeks ago knowing it was going to take some work and wanting to fix this myself so any information is greatly appreciated, Thanks.

 

You're definitely missing a sensor. You can tell by the large hole with the small threaded hole beside it.

 

That's actually supposed to be there. And there's no plug or sensor needed for that hole. That particular bell-housing is used on a few different models which use that hole. But for your vehicle application one is not needed so its left open.

I'm guessing you're stuck in limp mode because you have leaked most of your transmission fluid out. There's a good chance a line is cracked, or a front differential seal is bad.

I would not advise driving the car with low fluid - you risk burning out the clutch packs or blowing the pump. Which would require either a 5 spd swap or a whole new auto trans.

I suggest reading up on how to refill the transmission the proper way along with the proper fluid.

This would be the least expensive option to get you back on the road. Hopefully in the process you can spot the leak as well and you have not damaged the trans and can continue to drive it.

Good luck!

Jason