I had a blinking check engine light and rough running the other day in my 2003 A4 1.8t cab. Pulled over to check, and the dipstick tube was loose. I had just changed the day before and 100 miles ago, so I pushed it in tight and took off, no more blinking or roughness. A few minutes it comes back, and I notice the dipstick is loose again. Get to playing with it, and the plastic tube disintegrates. I do some searches and stumble upon an aluminum foil plug solution until I get the new tube. That seems to work fine, no CEL blinking/roughness. I get the new tube, pull the temporary foil plug out and try and pull the orange dipstick pieces that had fallen in the tube with no luck. They get pushed in engine. I replace tube and start car - the roughness and blinking CEL are back. I drain the oil, try and flush the pieces by running the oil through the dipstick tube, again to no avail. All the pieces are still in the engine, and the engine rides rough with the CEL blinking. I am positive that this is all because of the tube, because when it was plugged it ran fine (for 100 miles). Has anyone experienced this, or have any suggestions? I was only got error messages with my OBD2 reader, and although I have a VAG-COM plug, I do not have software on my current computer. Any suggestions on software would also be appreciated.