Trueblue

The day following a 70,000 mile service on my 2016 CD including fill up of Adblue tank my Check engine light came on (constant) followed a few miles later by the 1000 mile shut down message. This occurred probably with 150 miles of service so I know the Adblue was full.
This is the the 3rd time I’ve received the shut down warning in the CD. The first time it was corrected and the recall modification was done. Second time, warning came on after 75mi following top off and then then dropped from 1000 to 500mi in about 50 mi and then over next 200 mi dropped ultimately to 100. I was driving cross country first stopped at Louisville dealer that topped off and reset. Then stopped in KC dealer for a check before heading to Denver where I topped off before crossing mountains. Had the Las Vegas dealer check out and attempt to diagnose earlier issue. They replaced NOx sensor and level sensor. That was at around 40,000mi. Have not had an issue since until current problem.
I was on another 500 mi trip when the current warning occurred. Warning came on with 500mi and over 200 miles dropped to 30 by time we arrived at P dealer. They attempted a reset with PWIS. No success. More fault codes came up including NOx sensor. That dealer still has car and trying to get it in to their service schedule.
The dealer has already said they don’t have a lot of experience with CDs.
Here are my questions:
I think I can still start the car as it has 30 miles to go. I’m thinking of returning home, 250 mi, without shutting motor off. Will I trigger something else once below the 30 mile limit that will shut down? Is it worth the risk?

Is the Adblue system in VW and Audi Diesels the same? These dealers might have more experience in diagnosing and servicing Diesels than the Porsche dealers.

Has anyone else out there had experience similar to mine. How was it repaired?

Bottom line: can I trust this CD? I love the car. Crossed country with it 3 time and many more long distance trips some towing my other car. I’ve owned it 5 years from new and hope to have another 5. While emissions is warranted for several more years the long distance driving and driving in remote areas gives me pause about keeping this CD if there is not a clear diagnosis and permanent solution for what appears to be a more chronic issue.

I welcome your response

bdronsick

Honestly I would just grab a Foxwell tester and clear the random AdBlue countdown whenever they occur. Now if this is accompanied by a recurring engine light indicating serious issue that's another story altogether.

I'd start by clearing the AdBlue nonsense and drive it and see how it goes. These are generally very, very reliable vehicles. 170K+ on mine its a DD an no real issues to speak of. Ever

Trueblue

Thanks. I saw your post about a foxwell in another thread, seems like a no brainer for a diesel owner.
however my problem is more than a reset. It’s at dealer. They tried reset. No success. There are apparently other related fault codes. The dealer has not had time to investigate the other codes and repair.
My warning is down to 30mi. I have at least 350 mi of fuel left and would have a drive of about 250 mi to get home and would not need to shut off motor. I’m going to chance that I can make it. If not PCNA/AAA can pick me up.

Trueblue

Here’s continuation of my Adblue saga:
I retrieved my Cayenne from the dealer and drove 250 miles to my home dealer. When I started out Adblue warning was down to 30mi. I was cautioned by the dealer that because of NOx fault codes indicated more than a problem with level of Adblue, they were not sure if when I ran through the remaining 30 mi the car would go to limp mode. It didn’t. I made the 250 mi without turning engine off. Also learned that if I needed fuel I could open fuel door as long as I didn’t lock doors.
At the home dealer they are replacing NOx sensors and clogged Adblue sensor. (Picture attached) Does not seem to be an explanation of the cause. Can anyone explain?

hope this helps anyone who runs into similar issues.

Neil4speed

Really odd, and might be my miss on reading, but you did try the reset procedure of course? putting it into accessory and letting it sit there for 30 seconds?

I had a similar issue where it didn't reset properly. A rural mechanic was able to reset it with their generic code reader.. so I am thinking this is more involved.

bdronsick

When AdBlue refuses to reset, or OBD throws an aberrant AdBlue countdown, the only fix is to use the Foxwell (or equal) Chinese scanner to clear it, or else PIWIS at the dealer

Foxwell is only $100 or so for unlimited use. The dealer isn't as kind

bdronsick

No one (especially Porsche dealers) has a grasp on the fantastically complex constellation of DEF/DPF issues with the EPA's so-called and short-lived (and now-defunct) "clean diesel" initiative

(IE PCNA Turbodiesels are incredibly rare; mechanics almost never see them)

So you can replace every horrifically expensive exhaust component over and over again chasing these elusive phantoms, and never fully resolve them

Or instead you can simply clear any and every DEF/DPF code as they randomly arise, and drive peacefully for the 15K-30K+ miles in between each inevitable apparition

Bottom line: everything DEF/DPF actually takes place between the engine and the rear-view mirror. Like an accident that occurs behind you; unfortunate perhaps, but not actually your problem

Drive away

Trueblue

I agree with all you’ve said. Dealer has already replaced the complete system of sensors, injector, pump. CD is still throwing fault codes. They have attempted reset multiple times. Now they’re thinking it is a DME. Which is on back order. Seems no one has experience to diagnose issues with this system. All dependent on computer diagnostics. I’m under full emissions warranty for several more years or I would take it to an experienced independent diesel shop.

pital

did they resolve your issues? Having the same issues with our diesel 958.2.

bdronsick

Again folks, if you're gonna drive these Porsche unicorns you either need to 1- keep a Foxwell NT 530 on board to eliminate these insipid DEF "countdowns" to death, or if your jurisdiction allows 2- simply throw all the dieselgate junk into the dumpster and flash the ECU to forget it

Option 1:

Option-2:
https://www.rawtekinc.com/collection...d-not-included

Either solution works, but #1 is vastly less expensive

pital

I hear ya but ours still under warranty. In two years have had zero issues. Out of the blue this came up. They’ve replaced a number of parts the count down won’t clear.

bdronsick

I’ve never seen an AdBlue message Foxwell can’t clear. Doesn’t affect warranty to try

pital

Car still with the dealer.

bdronsick

They’re gonna be useless Porsche only made a few thousand of these but there’s over a million Cayennes. Service departments never ever see them

polish

Depending on where you're located it may be worthwhile to call a larger dealer that has diesel tech(s) on staff still even if you have to drive farther.