Hi. I have a 2008 Porsche Cayenne S that has started to accelerate by itself recently and also seems to loose power. I have had the throttle body with sensor and accelerator with sensor replaced as they did show a code, but after the replacement of both parts I am still experiencing the same issue. Any idea what may be causing the self acceleration and power loss?
So an update on what seems to have been the issue. The issue seemed to keep popping up in rainy wet weather or after a car wash. Went through the while engine compartment, saw no wires damaged, sensors live readings were fine, no loose plugs etc. Then thought maybe the ECU was getting wet. While removing the cover below the windscreen to inspect it, I noticed I could see the fuses clearly which should be covered that is found under this cover on the driver side. Low and behold thanks to some idiot at the dealership that was too lazy to put the engine covers, fasteners etc back properly the fuse cover had moved half way down off off the fuse box as it had no fastners holding it down, and it was just over half filled with water. Car seems to be perfectly fine and all codes are gone since draining, drying and using water repelling spray in the fuse box. This box contains a fuse for the Engine control unit, high-pressure fuel injectors, throttle adjusting unit. So it seems this may have been the root cause at this moment in time.
Thanks for reporting back. Chalk another one up for the dealer, eh? Glad you found the problem.
What does it show for TPS and pedal position in live data?
I'm not sure. I can ask for that information
Ideally we want to understand if the computer if:
1. The computer is thinking you’re commanding more gas and as such it adds gas.
2. The computer is not thinking you’re adding more gas and yet still adding it
3. Something happening that’s not commanded by the computer.
Codes P0121, 0223 and 0123 all deal with high and low circuit readings at the pedal assembly. Either it was installed wrong, the unit is defective or there is a serious problem somewhere in that wiring circuit. P0513 is for an incorrect immobilizer for a faulty remote key entry system. P1575 is for electric cars.
Yes these codes are the reason we replaced the accelerator assembly. Key code could be because the remote needed a battery change. Guess the next step would need to be to get the wiring checked between the accelerator and the throttle body.
Code P0121 has to do with the pedal assembly, not the throttle body. How much did you get soaked for that? I'd seriously consider finding another qualified mechanics shop that specializes in Porsches.
The part was a Bosch throttle body as per unit that was in the car already for $180 and $80 fitment. A faulty throttle body could also be the cause of PO121 code from research I've done. Car was a responsive again after the change, but the self acceleration started again 2 days later
Who did you have it replaced by? A dealer? You should probably consider testing and/or replacing the accelerator pedal assembly.
I had the throttle body and the accelerator assembly (accelerator peddle with it's sensor comes as a unit) replaced by a mechanic that has been used by everyone I know for years. Even he was baffled when I picked up the car and the same issue ensued after he had test driven the car and it had seemed fine.
What are the exact codes?
Code I was shown a photo of was PO121. This lead to throttle body replacement, and when that didn't work I was told the accelerator assembly was sending incorrect voltage to the throttle body sensor when it was tested. I then got the accelerator assembly replaced. The car will literally go accelerate to 7000rpm 40+mph without me touching the accelerator once I start pulling off from a standstill. Then it would have the opposite effect where I could put the accelerator to the floor and the car will speed up all leisurely. It used to also rev to a constant 4000rpm while in park on the odd occasion before I had both parts replaced
Also had a PO513 code
This was before accelerator assembly was replaced
Before throttle body was replaced last link to picture was before accelerator assembly was replaced.
https://photos.app.goo.gl/7dJgiRq6Pif6sNgz6