Porsche installed the 997/987 Rear Control Module in a vulnerable location under the driver's seat, making it prone to corrosion if water enters the passenger compartment. Leaving the top open during rain, clogged convertible or sunroof drains, or bad seals will let water get into the car and pool under the driver seat, allowing moisture to enter the Control Module. Once the rear control module is exposed to moisture, corrosion will start and damage to the circuits will begin. Intermittent faults may start and eventually the whole unit will fail. Possible Symptoms of a faulty Rear Control Module
