# Audi TT OVERHEATING PLEASE HELP



## Christian_02_225 (Sep 20, 2016)

Okay so now that the weather has been warming up, my Audi TT has been acting very strangely lately. First, the symptom that caused this whole mess was caused by my dash pod acting up and making the car think it was overheating and causing the gauge to peg to the hot side. The A/C would kick off and the climatronic would also read outrageously high like 119*C. The car was never actually overheating though because my OBD-II scangauge read the right Coolant temp and the car had no signs of overheating whatsoever. 

At first I figured it was the Coolant Temp Sensor, so i got a brand new one, and when changing it, I somehow broke the return line fitting off of the upper elbow distribution pipe from the radiator. I lost a good bit of coolant from that broken line and on top of that, I lost coolant when pulling the coolant temp sensor, but not too much in total.

I had to let the car sit for a day and drive the old Mitsubishi Starion/Conquest to hold me over lol. When I installed the new pipe that I broke, I topped it up with coolant (G12) and ran the car. As I expected, It was doing the same thing; the temp gauge needle would randomly just start moving to the right as if it was overheating. 

I know the car was not actually overheating because I have a OBD-II scangauge mounted to my dash that shows me the coolant temps and it would always show a perfect 188-195 degrees Fahrenheit reading depending on how I was driving. 

At this point I was kind of at a standstill about the whole sitiuation. It did not make sense to me why the car was doing this. So I went under the hood while the car was running and looked around. When the car was fully heated up after a "spirited" drive to the store, I felt the bottom radiator hose coming out of the engine after the thermostat, and it was barely even warm, probably just from the engine heat. I felt the upper radiator hose and it was hot as could be. 

When I discovered this, I was sure that it had to be the thermostat either not opening all the way or partly stuck. I put a brand new thermostat in from O'rielly Auto Parts and lost a ton of coolant when doing it. When I was done, I topped up the reservoir and let it run for a minute. It appeared to be running fine but THE GAUGE PROBLEM WAS STILL THERE. I did some more research online and found out IT WAS MY DASH THE WHOLE TIME. I pulled the dash and tapped and thumped it and the gauge returned to its accurate position and the climatronic also changed back to normal. 

Now that I found the problem to the gauge shooting up, I now have another problem. 

Sorry for rambling but the next morning I drove it to school and realized that it heated up much quicker than normal and when just driving at 60 on the highway, the coolant temp were at 212+. After I had breakfast, I came back out to the car and it started ACTUALLY overheating. The OBDScangauge started going from 215, 220, 222, then I pulled over. I did not put in enough coolant and when I popped the hood, the reservoir was bone dry. I poured the rest of the water I had and limped it to the nearest gas station to fill it up with some filtered water. It took over 5 water bottles to actually fill it up . Dont judge me lol. 

Now the car is topped up on water and is not overheating but now it runs a few degrees hotter than it used to. Before I changed the T-Stat, on the highway, temps would be at 188-194, now they range from 194-203 on the highway. When Idling, the temps still stay below 210 at most after a hard run but never goes over. 

Do you guys think that I could still have air in the system, considering the bottom hose still stays cool or the generic T-Stat just does not work the same. 

Sorry for all of the rambling, I just wanted to give you he most info I could.... just PLEASE give me any advice you can think of. Thanks


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## lite1979 (Sep 9, 2005)

I would check the fans at 190 to see if they kick in. If not, you may have to replace either the fans or the radiator temp switch. Check for fan activity with the A/C on as well. If they don't turn on, radiator temp switch may be the culprit.

My car currently behaves like this and I have the radiator temp switch ready to go in, but haven't had the time to work on the poor girl.

Sent from my XT1254 using Tapatalk


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## Christian_02_225 (Sep 20, 2016)

Well the dash pod is still acting up and it will make the fans run on high sometimes regardless of the temps and even when they are "stuck" on high, the temps seem to be still a bit high. and when I say "stuck" on high, I mean the dash pod is messing up and making the car think it is super hot.


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## lite1979 (Sep 9, 2005)

Let's clear up a few things here:

1. If your gauge cluster/dash pod is reporting the temperature erroneously, get it fixed. It's like $300, but it's worth the piece of mind.

The gauge cluster gets its reading FROM the Coolant Temperature Sensor; that value never goes back to the circuit that controls your fans. There are actually two values that come from the CTS; one goes to the gauge/HVAC, the other goes to the ECU.

If your fans are on high, it's because either your coolant temperature sensor or your radiator temp switch or both are making them run on high. This is common if, for example, the low-speed circuit in your radiator fans is broken, or your radiator temp switch is defective. It is not caused by your gauge cluster being messed up. 

Test both the low-speed and high-speed function of your fans by jumping the correct pins from the radiator temp switch connector. If the fans test OK, then your radiator temp switch is likely at fault, or perhaps your fan control module is faulty.

2. Whenever you have to replace a hose or component of the cooling system, always burp the system to avoid air bubbles messing with the temp values. This shouldn't take too long unless your heater core is dry, too.

Also always replace the O-ring for the coolant temperature sensor in the coolant flange (distribution piece that comes off the head). These cannot be re-used.

3. It's possible that you put your Thermostat in backward, preventing proper flow of coolant through the radiator.


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## Christian_02_225 (Sep 20, 2016)

Well, to respond to the cluster problem, I removed it and kept it plugged in. Whenever I tapped the cluster and moved it around, the temp gauge would go back down to the normal reading and the climatronic reading would also return to the accurate reading. And this all happened in a matter of seconds. Whenever the dash pods temp gauge rises up, it also kicks of the A/C which is my main concern/problem.


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## lite1979 (Sep 9, 2005)

You can try fixing the stepper motors as mentioned in the UK forums, or you can send it out for repair. Either way, you need a functional temp gauge in the car, and as long as this one is messing up, you're putting your TT at risk.

Trust me: I had to replace the head gasket in my TT because the previous owner never took care of the small stuff. Nip this in the bud by fixing your temp gauge, then move on from there.


Sent from my XT1254 using Tapatalk


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## Christian_02_225 (Sep 20, 2016)

Well fortunately, I do have the OBD-II Scangauge, it's called the Ultragauge, and it is just on the dash pod over the screen with some velcro. I LOVE IT SO MUCH, it tells me the exact coolant temps, fuel level, RPM, Speed, it clears codes, reads codes, ETC. Either way, the scan gauge is so handy and cool looking. All of it is in a digital readout too so I get the exact levels of everything. But yeah I would never drive my car blind about coolant temps.... too big of a risk. 

Oh and also yesterday, I was messing with the VCDS and the dash again and I had the dash slightly pulled out but still plugged in and when I would wiggle the wires on the blue connector, the tachometer would go down and the dash would lose power so could it possibly be a short in the harness? 

When I scanned the Dashboard module with my VCDS, I got a few codes, one was 01177 Engine Control Unit sporadic: Cannot be checked at present, 00668 Supply Voltage Terminal 30 sporadic: Power supply too small, and just 01304 and 01305 but I think those last two I think are from having the aftermarket headunit installed. 

Just to add, the backlight behind the 3000 RPM mark sometimes flickers and sometimes when my high beams are on, the blue high beam indicator will rarely sometimes get a bit dim but not too often. 

I am starting to think that this could possibly be an issue with the harness. IDK we will figure it out


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## Christian_02_225 (Sep 20, 2016)

Oh and today I found some more things leading up to the problem. I got to school early and I was just sitting in the parking lot and the temp gauge was acting up. I started wiggling the whole dash pod again and the whole pod lost power and the tachometer dropped to zero and started jumping around. Whenever I would move the wires around, it would start doing the same thing again. I am starting to think that it is a short in the connector. I mean that's better than getting a new cluster, maybe just a stupid short in the connector. And I think the reason the car is running a few degrees hotter could possibly just be the new T-Stat. Maybe since it isnt OEM, it opens differently or something but it seems to hold a constant coolant temp so that's good.


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## fresh1 (Aug 29, 2004)

I had a similar issue. The dash cluster was faulty. Bought a new one. 

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## Christian_02_225 (Sep 20, 2016)

bump


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## Christian_02_225 (Sep 20, 2016)

Okay so i still have not resolved this issue yet. The actual cooling system is settled now but the cluster problem still remains!! Now that I have noticed that the tachometer needle will sometimes randomly drop and spaz out and go up and down and the whole dash will start beeping in a different tone too. I really think that it is a connection issue on the connector. If I move around the dash pod while it is acting up, I can adjust it to act normally again but while moving the connector, the dash turns off, it beeps at me and just goes crazy. I really need help with this issue as it is getting hotter and I really do enjoy having my A/C and A WORKING DASH POD Lol. I still get the 00668 Terminal 30 supply voltage too low : sporadic and I am getting more annoyed with this every day PLEASE help THANKS


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