Originally Posted by gedwar1

The Mercedes part number 580 000 021 (Mercedes) is the same bosh pump as part number 580 000 023 (Audi). Even the number stamped on the plastic is the same. You should be able to find a new Audi pump for around $200 by doing an online search by part number. After my first pump failed (burned up) the new pump stayed on too long, so I unplugged it before it fried also. I pulled out the relay box and found the relay for the pump stuck closed. I replaced the relay and no more problems.