Coolant temperature

**Rocketman666** · 07-05-2012,09:55 PM

Recently got a fault where by coolant temp not coming up to 90 degrees within the usual 5 mins.
The engine management light also came on around the same time. It looks to me that the thermostat is stuck open (coolant level fine and no sign of coolant in engine). This is the first car I've owned with a clever brain and lots of sensors. I am a DIY mechanic that is comfortable with most jobs.
My problem is that i need to confirm its the thermostat. I'm happy with the procedure with checking the heating element and checking the stat but I have no way of clearing the fault. Will the engine management light go out once I've rectified the fault or should I invest in an interface lead and some sort of software. I don't want to be running to my local auto electrcian every 5 mins throughout this car ownership.

Any advice on similar faults would be appreciated and recommendations for software.

**benjie** · 07-05-2012,10:11 PM

What car do you have and what does the engine management light look like?

Stuck thermostat won't ever show a fault code, either stored in the ECU or on the dash. Coolant temperature sensor... I'm not sure. In these situations, it's easier to change both of them, especially if they haven't been changed before. Coolant temp sensor generally causes the temp gauge to move quickly, thermostat generally causes the needle to drop at idle and go up/hold steady when driving.

Thermostat is about £20 (make sure you get the O ring too...), coolant temp sensor is a bit more, normally comes with a rubber O ring. Best to order the securing clip too as they tend to corrode.

Hope that's of some help!

**nevo** · 07-05-2012,10:13 PM

What was the exact fault code,the stat wont give a code?

**A4 Lad** · 07-05-2012,10:15 PM

As said, a stat is mechanical and wont throw a MIL on. You need to tell us what the fault code is that is stored

**Rocketman666** · 07-05-2012,10:29 PM

The car is a 2.0 SE 20V Petrol.
Sorry my wordiing in the first post was misunderstanding. I don't have the fault code and I have no way of checking. My current problem looks like a stat fault because the engine temp starts to raise after about 30 mins but only to about 70. The audi manual says that as soon as you unplug the output connector for the thermostat heating element (on the housing) a fault code is generated. I want to be in a position to buy software to communicate with the ECU so I can view/clear these faults.

**RuslanA4** · 08-05-2012,01:32 AM

Hi. You can buy cheap cable no problem, it will do for reading and clearing fault codes. In regards to your problem, open the ECU box and check the fuse in there. If its blown ECU will turn on MIL light. It was blown on my 2.0 20V and it threw MIL light. Replaced it, cleared codes and it was OK

**Rocketman666** · 08-05-2012,10:01 AM

Hello Ruslan

So was the blown fuse in the ECU causing the same issue with your coolant temp guage?

**RuslanA4** · 08-05-2012,03:06 PM

It was back in September last year when I bought the car, so I can't remember for sure about temp gauge, but it did cause few weird problems and fault codes. The fuse is located in ECU box beside relays. I would check that first before spending money on parts you may not even need

**Rocketman666** · 15-05-2012,05:51 PM

Update to this fault.
It was a faulty thermostat. Bought a new thermostat housing from Audi on Sat and fitted last night. Temperature now reaching and holding 90 degress celsuis.

Thermostat housing was £51 plus vat from Audi Edinburgh.

Thanks all for your help.

**rabmurray9121** · 16-05-2012,05:01 PM

Where is the coolant temp sensor located on the V6 2.5 TDI as i have the following fault code 18062 P1654 (01039 - Engine Coolant Temperature Sensor G2). Is it any easy job to change the sensor on this engine as i have been quoted 150 Euros from Audi to have it changed.