FergusH

I picked up my GT4 on Sunday and got this error several times on the way home:



An overheat error came up first but was then quickly replaced by this error, almost as if the car is saying "I'm too hot...wait, I only think I'm too hot".

The car is back at the dealer now and I'm driving the *exact* opposite of a GT4 (Cayenne, but even better a diesel Cayenne!). I'm sure it'll get sorted out ok but I'm curious if anyone else has seen the same problem.

Thanks.

Edit: I found a picture on the Internet of the overheat error I get first. The yellow caution message appears immediately after.

neanicu

It's probably a faulty thermostat. Very common on the 9A1s. I haven't heard of this problem on the GT4.

STALKER99

Did the coolant temp actually increase???

I'm not sure if the Cayman is the same as the 991 but I would get a similar error code on my 991 C4S but it was simply caused by an exhaust vaccum line that is poorly placed, since it would melt. My temps would be perfect though.

FergusH

No, the coolant temp was in the normal range.

csbear

Possibly a thermostat issue as mentioned by neanicu, which is not that bad if that's the case. Should be an easy fix then..

David Schacht

I had a similar problem with my 987 CS, it was a coolant temp sensor

BRNGT4

Have you installed an exhaust on your car? Is the Vacuum hose that actuates the exhust flap damaged or disconnected. If so that is your fault right there. The vacuum hose that attaches to the exhust if damaged throws a coolant error. why i dont know but that is the case.

BGB Motorsports

The reason that fault occurs like that is because the vacuum for the PSE is the same vacuum that opens and closes coolant doors for heat exchanger warm up and circulation. I think your guess is probably correct but without seeing the fault in the DME it's hard to be 100% certain.

One of our first conversions had that same fault til we wired the flaps shut on the aftermarket exhaust to determine the cause and then it was okay.

FergusH

No, totally stock. Hopefully I'll hear something today.

shewu

Completely OT and apologies in advance for hijacking, but CONGRATS! I only knew that you got the GT4 from stumbling upon this thread. Happy early Thanksgiving!

FergusH

Got a call from the dealer today saying the car was ready. Great! Five minutes after picking it up, exactly the same error appeared again. Not great. Back in the loaner Cayenne until after Thanksgiving while they fix my car.

bhk1004

Wow that sucks. Could post the original diagnosis by the dealer? I guess this second time it'll be something else so that would be nice info also.

BryanCO

What the heck! Doesn't provide a lot of confidence for that dealer...

sccchiii

very likely a stuck thermostat.

LexVan

We've had a ton of these on the 991 Forum. This is the change/cross over valve issue. IIRC. Search over there.