I am curious how many people here would let their car go 50 degrees past the redline temp because of something they got from Google.

I say go for it what do you have to lose. If the engine blows you can tell Porsche that you heard it was OK from the internet.

 

sorry.... no really. Nope. Sorry. I follow years of experience, knowledge of what overheating will do to an engine and more trust in my dealership than ... Google.

 

If the coolant could stay liquid, your engine might survive 300 deg.
However, at about 265 deg your coolant will boil and turn to steam.

 

Very interesting, Fester. We both were part of the first batch of US-bound C4S builds and both have had the same problem! Maybe it's our scaldingly-hot espresso interiors!

I had this happen to me a year ago when on a long highway drive from Boston to NYC in high ambient temps (100degF-ish).

I turned the car off on the shoulder and let the temp drop back down to normal. Restarted the car and temps stayed perfect.

I brought the car in for service the next day. They said that they saw the code and insisted that the problem was software related. They did an update to the software for the instrument cluster and said that would take care of it.

I was (and still am) skeptical of the "fix", but to this day (5000+ miles later) I have not had the problem return.

 

Maybe porsche has a high pressure system, but at 300 degrees, you would need to have almost 60 psi system to keep the water in a liquid state, I am guessing that maybe on the racing models, they may have a system that will go this high but not normal on a primary street vehicle. My C2S also stops at 250 and I run at around 200 constant so yea, thinking a dealer visit is needed.

 

Fester, any update on what happened?

 

It's one of those things that they need to "reproduce" to prove it out.

First thing they do is to "look" for any "fault codes" by hooking up the computer. Nothing found.

Then they checked the coolant line for "leaks" - no traces.

Then they drove the car and the coolant stayed pinned at 194F.

All of this after showing them the photograph and call at the time of the incident.

The only thing I got out of it is PDCC and PCM software updates and perhaps loaner Hybrid cayenne S.

Well in 15 months of ownership it heated up to this level twice...so I don't know....I'm beginning to wonder how "reliable" these cars are????

May be as per Brianja, the software could fix this issue...but they couldn't find any fault codes

 

I had my car go over 194 a few days ago, the low coolant warning popped up. I drove home and added some coolant after it cooled off, thought that was the end of that. Started the car, same warning popped up and kept popping up. Took it to the dealer, they tell me it's one of the vacuum tubes that has gone bad and is tripping the sensor. They kept the car for a couple of days to figure out which one and replace it. Next time it happens to you have them check your tubes.

 

There's also a possibility of the sensor going bad.

My first car was an old POS pontiac that would occasionally overheat. The old-school fix was to run the heater at full blast. Natch the car would only overheat in the summer, so it was mildly uncomfortable, but that technique works. Next time this happens, turn the temp on the HVAC as high as it will go, turn off the A/C and put the blower on max. This will help to cool down the coolant. You won't enjoy it too much. You might want to roll down the windows.

All of these new cars with their fancy computers and sensors are really great in helping the techs diagnose the car. Except when there are no codes, then they have to fall back on experience and knowledge.

I think these cars are pretty "reliable", it's just that unfortunately for you, you've got one of those intermittent issues that can be very difficult to diagnose. Best of luck!

 

Do you think the car is actually overheating, or just incorrectly reporting overheating? My digital readout never moves from 194f. Are both the gauge and digital readout reporting the same temp.?

 

Yes it overheated. Both gauges showed, heat was radiating out and fans were going 30 minutes after while it was parked with car completely turned off

 

I guess next time I just let it go all the way with warning light (just like Brianja) so it actually throws the fault codes. Then get it addressed - makes sense what you guys are saying...vacuum tube or sensor ....may be..

 

If the temp sensor periodically malfunctions for whatever reason and sees the temp as higher than actual temp, both gauges will show the wrong temp. It will also tell the car to keep the fan running because it thinks the temp is higher than it actually is. Do you have coolant boiling over when this happened? I found my car is always hot when you walk around the back even with normal driving.

Kind of like a cheap tire pressure gauge telling you it is 45psi when it was only 35psi.

Just a wild guess on my part. Hope you get it resolved.

 

There was no coolant warning sign - however, they topped it off a little bit (level was a little low).

I'll continue to drive it hard and see if it happens again. Just a little bummed that this issue is still open without root cause...

 

Here's the message I got. Again, the coolant was low but the message stayed even after I topped off the coolant. Dealer told me it was a bad vacuum tube, I wonder if he meant a change over valve. My car is still at the dealer, I'll update this thread when I get the paperwork with the details of what was done.

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