Warnings Problems of Porsche Cayenne

On the afternoon of June 24, 2026, at approximately 5:40 pm, I experienced a severe, sudden braking system failure that directly caused a rear-end collision. I was driving my 2023 Porsche Cayenne e-hybrid on the highway, traveling to a concert scheduled for 7:00 pm. The highway traffic was heavy and slow-moving (stop-and-go). I was cruising at a moderate speed of approximately 40 to 50 mph. The vehicle ahead of me applied its brakes and came to a gradual, normal stop. I was maintaining a very safe following distance of approximately 30 meters (around 100 feet) behind that vehicle. As I perceived the traffic stopping, I immediately attempted to apply my brakes. However, the brake pedal instantly became extremely hard, felt completely locked up like a stone, and was impossible to press down. Despite having ample distance to stop and applying all my body weight and force onto the brake pedal, there was zero brake assistance from the vehicle, and the brakes failed to engage. The onboard forward collision warning and automatic emergency braking also failed to prevent the accident. As a result, I was completely unable to reduce the speed of the car, and my vehicle rolled forward and collided into the rear of the car in front of me. This was entirely a mechanical/electronic safety system failure. The vehicle is currently available for inspection, and I am requesting a full diagnostic download of the edr and dme data before any repairs are performed.

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Multiple dash messages indicating failure of driver assistance systems.

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The car was driven from cheshire, CT to old tappan, NJ about 90 miles, just under two hours drive time. Combination of highway and back roads. The car was in drive in comfort mode proceeding slowly (approx 20 mph) down a street within a condo complex. As I approached the driveway I lightly braked, turned into the driveway then lightly pressed the accelerator to bring the car up the driveway apron onto the single car length driveway. At that point the car accelerated to what felt like max power. The car accelerated uncontrollably causing the car to advance in a right turn through the closed garage door striking a garaged vehicle in the right rear quarter and the right wall of the garage. Fortunately no one was hurt but this could have resulted on severe injury or death. No pre warning lights just a slight burning smell just before. This unrequested acceleration occurred twice before the crash incident leaving a traffic light from stop. Porsche has analyzed the car and find no fault. The insurance company has sent an adjuster. Damage estimated at $73,000. 00.

The transmission has quite a bit of slop or play when placing it in park. I do not believe it could be parked safely in a residential driveway. Tranny knocks a little in low gears.

See all problems of the 2005 Porsche Cayenne 🔎.