Coolant temperature sensor 1 B1 location

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Hey everyone, I've recently scanned my car with VCDS and found that strange values at the coolant temp sensor.
Been trying to locate the radiator sensor to no avail.
Searched the entire web, and only thing I found was that some person claims diesel engines to have only one cooling sensor at the engine.
My car is a 2.0 tdi 8V, CRBC.
I couldn't find any sensor on the hoses going to the radiator, neither I have managed to locate the engine sensor.
Would very much appreciate some help where and what to look for.
 

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depending on the output of your engine it either has 1 or 2 coolant temp sensors that aren't part of the thermostat. but with vcds finding 3 temp and 2 acting up... you got 2 sensors that aren't the thermostat... look below for the locations of both sensors (if you got 2)

The coolant temperature sensor on the Audi A3 2.0 Tdi 8V CRBC is located in the coolant pipe, below the air intake pipe and behind the right cylinder head. It is also mentioned that the sensor is right next to the water pump, between the water pump and oil cooler. To access it, you may need to remove the throttle body, throttle body air duct, and intake manifold brace.
 
northpole said:
depending on the output of your engine it either has 1 or 2 coolant temp sensors that aren't part of the thermostat. but with vcds finding 3 temp and 2 acting up... you got 2 sensors that aren't the thermostat... look below for the locations of both sensors (if you got 2)

The coolant temperature sensor on the Audi A3 2.0 Tdi 8V CRBC is located in the coolant pipe, below the air intake pipe and behind the right cylinder head. It is also mentioned that the sensor is right next to the water pump, between the water pump and oil cooler. To access it, you may need to remove the throttle body, throttle body air duct, and intake manifold brace.
Click to expand...
Thank a bunch!
I thought it is the one I marked with a red arrow and changing it would be a diy.
I drove around 200km on the motorway today and the car warned me several times that the coolant temp is too high, and right after that it says to check the coolant level.
When I stop and open the hood without turning off the engine - the fan works but not at full speed and all of the coolant is either already "thrown" out of the coolant reservoir or is being discharged at the moment from the bottom of the reservoir.
This used to happen randomly in the past 6 months, but since last week it happens on every drive of the car - no matter if it is a long or short drive.
I am a bit confused as there is no evidence in VCDS scans for the fan to be working improperly, still it does not reach full capacity, and when I turn off the car, it ceases to work.
It even ceases to work when the engine is running and the car is stationary.
I also do not understand why the coolant is being discharged from the reservoir.
 

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because the coolant somehow gets to much pressure... and escapes through the venthole made especially for this purpose... 9 out of 10 times this comes from a bad waterpump ( but if that was the case you'd have coolant leaking on the timing side too... so it probably is the 1 in 10 times option which is the lid from the expansion tank causing it... it has a build in pressure relieve valve... sometimes they all of a sudden fail and pressure doesn't get the chance to escape resulting in the expansion tank dropping coolant out of the venthole

so i would start with the cheapest solution and that is replacing the expansion tank lid (cap or whatever you want to call it) and see if the problem goes away.
 
northpole said:
because the coolant somehow gets to much pressure... and escapes through the venthole made especially for this purpose... 9 out of 10 times this comes from a bad waterpump ( but if that was the case you'd have coolant leaking on the timing side too... so it probably is the 1 in 10 times option which is the lid from the expansion tank causing it... it has a build in pressure relieve valve... sometimes they all of a sudden fail and pressure doesn't get the chance to escape resulting in the expansion tank dropping coolant out of the venthole

so i would start with the cheapest solution and that is replacing the expansion tank lid (cap or whatever you want to call it) and see if the problem goes away.
Click to expand...
Tried replacing the cap long time ago, no difference.
Water pump and timing were replaced in the local Audi service center 3 years ago.
I believe the thermostat is also in good working order as the hose going into the radiator gets warm.
Today I decided to book another appointment with a local service. They do Audi's so I really hope they can fix it for once.
I also hope this thread is being useful for other having the same or similar issues.
 
stuff being replaced a long time ago doesn't mean it's working properly now, but since you got it booked in they'll sort it out. worst case you've got a blown headgasket.
 
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