Diagnosis...2 bad wheel spin sensors
 

I started a thread a week ago regarding a CEL on the way home last Wed. night. No symptoms. Filled it up and checked the gas cap, which was tight. Drove it 20 miles without incident. The next day, thinking I had an evap problem, I drove it a couple of miles over to the gym. The trip over was fine.

I started out of the parking lot onto the main road after class, and clunk, click, click, click (PSM light flashing), with a message that the "All Wheel Drive System Overloaded."

I managed to limp to the shoulder with flashers on. Turned the PSM off. Started forward, and it all happened again while automatically turning the PSM back on. I turned the PSM off again. This time, the following messages came up:

- Fault Steering Lock
- PSM Failure
- ABS Failure
- Check Engine
- Chassis System Fault
- Fault Electric Parking Brake
- All Wheel Drive System Fault

I drove forward and back a little, and didn't get the "limp" again. I returned to the gym parking lot and drove around for a couple of minutes to see if things seemed (otherwise) normal. Everything seemed okay. I just had a colorful display of clever icons lit up everywhere. So, I drove home without incident.

I had the car towed to the dealer Friday morning. The initial thinking was a bad AWD module, which the dealer had seen about 4 times in the past couple of years on 2012 and 2013 models. The tech disabled the AWD module and attempted to drive it, and the same thing happened--not the AWD module.

After scanning the vehicle and inquiring with Porsche for good measure, they figured out I had two bad wheel spin sensors. The one in the front was registering 15-20 mph two slow, while the one in the rear said it was going in reverse. Needless to say, the car's brain had no idea how to process this.

The report now is that all four wheel spin sensors have been replaced--as is the way they are always replaced, as a set. And, the car has been driven yesterday and today without incident. The noise I heard and reason the vehicle wouldn't move was likely the ABS system applying the brakes. The PSM system was also likely trying to mitigate what it perceived as wheel spin.

According to my advisor, this is not a common problem. They hadn't seen it, and they only found one other similar situation when researching it.

Wheel spin sensor
 

Had the same problem on 2014 Cayenne S. Was 680 to fix at the main dealer. 280 was the sensor cost. They only changed the one that was not outputting a signal.

Symptoms were the ‘All wheel drive system overloaded’ message and felt like the fronts were being braked but the ABS system.

Anyway all resolved and the diagnosis on the above thread was spot on!

Had same with my ‘08 S model, replaced both rear wheel speed sensors.

Paul - there is a recall for these sensors on the 958 series Cayennes (which your 2014 is..) You should be reimbursed for any money spent on the sensor replacement. Contact Porsche and/or punch your VIN# in the NHTSA recall database lookup tool.