2007 Audi Q7, Battery Monitor with Water Damage

This customer brought their 2007 Audi Q7 in with a concern that their battery was dying overnight. They had just installed a new battery and it was dead in a matter of days. We have seen several power-related concerns with these Audi Q7s. The root cause is usually a clog in the sunroof drain or the HVAC air box drain. When these drains clog up, water overflows into the passenger compartment at the driver’s feet. Keeping up with your maintenance and having these regularly cleaned is a good way to avoid these problems. The Q7 has a battery located under the driver’s seat and several wiring and electrical components under the driver’s floor mat. When they are allowed to sit in water these sensitive components can become damaged. We have seen wiring harnesses and fuse blocks most commonly damaged. In this case, there was a damaged battery monitor control unit. The unit was damaged and the wiring harness going to it was also. In most cases, we like to use new factory quality components, but this was an expensive little unit. The customer chose to have us source them a used unit. We replaced the unit along with the end of the wire harness. This solved the customer’s battery discharge problems. With the same basic design, we have seen this problem on Porsche Cayenne and Volkswagen Toureg SUVs as well.