LSR

I just drove my new 2022 base Cayenne on its first trip about 250 miles from home. The car has 4800 mi on the odo. After parking the car for about 10 minutes, when I returned and tried to start it up again the dashboard lit up with something to the effect of “Transmission failure. Car may roll and reverse may not work. Engage parking brake.” And the car would not start. After shutting it off, opening the door, and trying again, same thing. Tried again, and this time the car started, but another warning message flashed that auto stop/start was disabled and the CEL light came on. Fearing the car wouldn’t start again if I shut it down, I kept the car running for the rest of my trip until I reached my destination. I’ll try to start it tomorrow after the car’s had a night to just sit.

Has anyone seen this transmission failure warning before? The transmission obviously still works but I have hundreds of miles ahead of me to drive it back, and before I did that I thought perhaps someone on the forum has seen this issue before and knows what the problem may be.

Schnave

Sorry for your troubles, LSR. Two things come to mind:

1. Check your battery voltage prior to start tomorrow. Low battery can cause your warning panel to light up like a Christmas tree.
2. Look under the transmission for a puddle of transmission fluid in the morning. There was a recall for a bad weld on 2020 Cayenne external transmission oil pipes, pictured. Link to recall here:
https://static.nhtsa.gov/odi/rcl/202...0V271-3634.pdf



Here’s another thread discussing the “Transmission Failure” warning, but on eHybrids. Sorry to say, they had their transmissions replaced.
https://rennlist.com/forums/cayenne-...n-failure.html

LSR

Thanks, Schnave. Good advice about checking for a leak, even though the problem previously was on 2020s. I’ll check in the morning. I’m thinking (read: hoping) this was just a software glitch and things will be back to normal come sunrise. The car’s got an appointment with the shop already for next week after I return, and I’m curious to see what the codes say. I’ll keep this thread posted with whatever I learn about the issue, in the event the same thing happens to someone else.

Schnave

Oops! I must need glasses. I thought it was a 2020!

Good luck tomorrow morning; hope it gets you home safely.

Schnave

@LSR So how did it go? Did your Cayenne’s transmission get you home?

LSR

Yes, the car got us home without incident. Thanks for asking. I’m pretty sure it was a software glitch. I let the car sleep overnight and in the morning I looked for leaks like you suggested. There were none, and the car started fine. As expected, though to my dismay, the CEL was still lit. But there were no transmission warnings and the car drove normally (but for the CEL). We drove a few miles to where we were going that day and parked. When I returned 5 hours later, the car started again without drama but, to my amazement, the CEL light was gone. It’s as if the previous day’s excitement never happened. Weird.

I’ve got a date with service on Thursday and hopefully they’ll read out some codes that will explain what happened. If it was just a software issue, though, we may never know. We’ll see. I’ll post what I learn.

Tbounds

I read over this and I have a cayenne built in sept 2019 , but that doesn't tell me when the oil pipe was built . you have to look at pipe my dealer says that there are no recalls on my vin . I guess even though mine was built during the month in question , but the pipe was built before then.?

LSR

Here's an update to my initial post. My car with its transmission warning has been in the shop for the past two days. According to my SA, the car threw "all sorts of codes" including some "failure to communicate," but there are no hardware failures. So they are attributing the problem to a software glitch, which is what I suspected happened. The tech reprogrammed the entire car and it's apparently working fine. Here is what is stated on the repair invoice: "5497 MULTIPLE NO COMMUNICATION FAULTS/SOFTWARE INCOMBATABILITY FAULTS. GATEWAY REPROGRAMMED, ENTIRE VEHICLE RECODED. NO FAULTS PRESENT AFTER TEST DRIVE." These are the fault codes:

• P253200 - Terminal 15, voltage implausible
• U041600 - Data bus - fault value received
• U102500 - Check air conditioner control unit fault memory content
• P056800 - Cruise control stalk - signal implausible
• U041400 - All-wheel-drive electronics control unit (PTM) - signal implausible
• U014100 - Rear-end electronics control unit - no communication
• U041500 - Control unit for brake electronics (PSM) -signal implausible
• U016400 - Air conditioning control unit - no communication
• U014000 - Front-end electronics control unit - no communication
• U015500 - Instrument cluster control unit - no communication
• U014600 - Gateway control unit - no communication
• U104500 - Lane Change Assist control unit (master) -no communication
• U019900 - Driver-side door control unit - no communication
• U105400 - Central computer control unit -no communication
• P 162400 - Engine control indicator light switched on
• P 157000 - Engine Control Module (ECM) disabled
• P 170100 - Transmission control unit locked
• U010300 - Lost Communication with Gear Shift Module

Perhaps the strangest part of all of this is the ECL light turned itself off all on its own. The tech told me once that light is lit, it should stay lit until manually reset via the OBD2 port.

Right now, I'm chalking this up to random chance. If it's more than that, though, it may happen to someone else's car. If anyone reading this post does experience anything similar with a 2022 Cayenne, please post what happened. In that event, it may be appropriate to bring the matter to Porsche N.A.'s attention to investigate.

MiFast

My Cayenne(2019 Base 151K miles) just started doing this to varying degrees which seemed to reset either with turning the key off for a couple minutes or overnight. Usually transmission based but also get the "SOS warning failure" which at times will go repeatedly on and off. Yesterday it seemed to escalate and I haven't trued to drive the car yet today but obviously it is going to the dealer. I think it is a computer issue since it runs as it did new and shift smoothly and normally. Very odd. I guess the $500 computer reset will seem cheap considering the alternative. Anyone else having this issue?

Vapordan

Did they load test the battery? Sounds like a battery issue. I fail to see how software can throw these many codes and then magically fix itself as the root cause. Software is not that smart.

MiFast

Nothing has been done yet. Car seems to be charging fine. To me it seems odd that you get warning messages that appear. Then aren't seen for a couple weeks and then reappear. To me it seems like there is a computer issue. An issue that has been happened about 5 times in the last 6K miles is that it sometimes will not move out of gear. Meaning it is very difficult to move from drive to reverse. Sometimes I've tried to restart the car and that works. Sometimes a combination of locking and unlocking. Why would the car drive normally and then all of sudden while driving a warning light or my case a few. Starts w transmission, then adaptive cruise is in operative and reverse function may not work.
Possibly the issue is the power isn't at the correct level but my gauge always generally shows the low 13 volts
It will be interesting to see what codes got logged