RJD17

Hi All,

I have a 2005 Cayenne 955, V6 w/180,000 miles. My girlfriend is the original owner and it's now her second car so I've been using it here and there so the car doesn't sit for too long. The car runs great. A past issue was, it use to buck when accelerating. If I drove it in manual and shifted myself it was smooth. That problem was corrected (by her family mechanic who maintains/services their cars) but now every once in a while the car has had hard downshifts. If on the highway and hit the brakes to slow down, the car bangs into lower gears as you decelerate. It's weird because it's intermittent.
I mentioned it to the mechanic and he recommended to sell it before it becomes costly problems lol. He's real busy, plus his vacation is coming up so I'll try to troubleshoot and eliminate as many problems as I can.

Upon starting the car, there are messages on the instrument panel:

1. Brake pads (Pads are low, I'll replace them asap)
2. Washer Fluid (fixed, topped off fluid)
3. Dipped Beam (fixed, replaced lamp)
4. Brake Light (fixed, replaced lamp)

after ten seconds of the car running...
5. Four wheel drive faulty

The airbag light is also on (found broken wire off yellow connector under drivers seat. Soldered back on and tie wrapped connector higher up in the seat to avoid it catching when seat is moved)

While driving car, Battery/Generator Warning appears. I check battery under drivers seat (only one in this car). I get 11V when car is off and dropping because fan is running... that's another issue lol. I start car and read 13.7V. This is still original battery. I replaced it. While replacing the battery I notice water under the drivers side carpet (still investigating... probably a clogged drain)?

Now when I start the car I still get Brake pads warning (obviously need the be replaced) and after ten seconds the Four wheel drive faulty. I've checked all fuses under hood and left side of dash. Removed them, cleaned and reinstalled. Still same message. I took off all plastic covers in engine compartment to look for any damaged wires and also cleaned whole compartment. Now when I start car, engine light is on and car runs rough...
what did I touch lol? Maybe something got wet? That was last weekend and car sat. Last night started it up and still rough. Tried to drive around block and it's undriveable. Barely made it to 20mph. Could it be electrical/computer problem? Anything I should check to rule out other problems? I don't have a durmetric and was hoping your experience could point me in right direrction.

Sorry for the long post... I'm a new member and still navigating around the site. Any help or links would greatly be appreciated!

Thanks, Ralph

touareg

Check this first: https://rennlist.com/forums/porsche-...-flashing.html

Also check all the drains around the cowl area for water pooling. Thread above has that info for the major culprits.

Check all the connectors for the MAF and Throttle body.

Transmissions have known valve issues.

RJD17

Thanks for the input touareg!

RJD17

here's a list of fault codes I have:

P0480
P0441
P0421
P1517

0668
0087

0532
0908
1320

0323
1135

0709

Shawn Stanford

^This. Super, super easy fix. You just need a couple sockets, a wire stripper, some electrical tape, and a few zip-ties.

This is also a super easy bit of maintenance. There are couple of Youtube videos about it. I pulled the the rubber piece completely.

I was having valve body symptoms ('bang' when braking at low speeds). I had the transmission flushed and it seems to have helped.

RJD17

Thanks for the info Shawn!
I'll put flushing on the list. I have no knowledge or record if the tranny fluid and filter was even ever changed.
I blew out sunroof drains and since I had the car up and front wheels off to change the brake pads, I removed the wheel wells to make it easier to clean out those drains. Brakes are done, new sensors too. I still get brake pad warning message though... maybe connector didnt make contact? I'll have to unplug them and check continuity on sensors, then I'll jump out wires to car to see if that clears message.
I also lifted carpet and dried it out. Checked that harness like touareg said. I had same black wires spliced as him. They looked good but I soldered and heat shrank anyway. Also same with the brown wire. I had a few Red/yellow wires that weren't connected... spares maybe? or where they splice and rotted apart? The insulation was even with the copper like a clean cut at the end but had green oxidation. There was some tape but just laying with harness, like it fell off somewhere. I just put tape on ends of each individually for now until I figure out if they're supposed to be spliced together or not.

Shawn Stanford

My '05 base has about the same mileage as yours. I get rough run on startup as well and a CE light. I'm sometimes down on power at low rpm as well. I pulled the code and it was something about low fuel pressure. It could be that I need another set of fuel pumps. Mine originally went out around 110k or so, and I replaced them with a pair from a wreck. If that's the problem, I'm more than happy with getting 65k miles out of a $150 set of fuel pumps.

So, you've replace the battery and fixed the wiring and cleaned the drain plugs. What codes are you getting now? The dozen on that list?

RJD17

The rough idle I corrected. It was my own fault. The engine compartment was grimy and I cleaned it and rinsed off with water. I left hood open to dry out in the sun and the next day when it was dry, I tried to drive it and was really rough. I read about checking for cracked coils so I removed a coil and it was wet. Water seeped through the gasket down by the sparkplug. Everyone was like that. I vaccuumed it out and blew compressed air to make sure. Dried up coils and few hours later I reinstalled them. Car runs smooth now.

Upon start up I get Brake Pads Workshop. Then I hear Radiator Fan kick on. About ten seconds later I get Faulty Four Wheel Drive. While car sits there idling I can hear fan slowdown then speed up. It runs even after car is off up until about 15 minutes. I think that's normal. Also when idling if I raise rpm up to 1800, I get Battery/Generator Warning. Before starting I had 12.4V at battery. When engine running I get over 13V. Gauge reads the same on dash. New Battery and seems like it's charging.

I have an ICarscan that I used to get fault codes. I cleared codes and retested. I get 3 faults. I'll post pics.

Shawn Stanford

The only thing there ties to the motor is P0441. Google found some stuff. Give it a look.

RJD17

Thanks Shawn,
It looks like the fan control module could be the problem. I'll do some more troubleshooting this weekend.

nodoors

Sounds like she handed you quite the pissing baby! haha

RJD17

yes! hahaa
I've been checking off the fault list. A few more to go. Most problems were electrical... corroded wires, bad sensors, battery, etc.

Strangely enough, it's been fun learning about, troubleshooting and fixing the car. Thanks to everyone's help.

I just hope the Panamera has less gremlins since we'll be shopping for one by years end.

Shawn Stanford

My plan is to get my Cayenne to 200k and then to start looking for a Panamera. 50k to go!

RJD17

I found the reason the fan was always running... connector was corroded and broken wire. Cleaned up green oxidation as best as I can and soldered wire back on. Filled connector with silicone and reinstalled fan. Problem solved.