Coolant temp sensor

rickparmar

rickparmar

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Scanned my S3 and this came up,

Its easy to replace and will get part this week, but what i want to know what does it mean exactly,

i know it effects

It can cause the ecu to cut back on boost,
It can cause soft limp mode and poor running.
It can make you feel you have a boost leak and
It can provide false reading that could cause lean or rich running.
It could cause strange dash temperature readings.

but what exaclty does it do, and how does it work

Thanks :)
 
Take it on face value, its a 'coolant temp sensor'.

It's a sensor that measures coolant temperature :)

But seriously, the whole engine management is optimised (well, generically optimised as factory settings can be) for 'normal' running conditions and temperatures. Normal meaning working temperature. If the ECU is being told that the temperature is anything other than normal then it is programmed to assume that either the engine is on cold warmup or overheating/running hot (due to hard driving) so ******* various settings to protect against engine damage.
 
You say its an easy job?? Ive had a look in the haynes manual and it looks pretty tricky!! Mine has obviuosly gone aswell any chace of taking a few photos when you do yours?
 
took about 15 minutes to change mine on the A4, just unplug the wiring, remove the circlip that locks it in place and lift it out. Make sure you take the top off the expansion tank first to release any pressure in the system, otherwise you get a facefull of antifreeze (like I did)
 
rickparmar said:
...and how does it work
Click to expand...

The coolant sensor is a thermistor. Basically a variable resistor which is affected by temperature. The ecu takes this resistance reading as the car's coolant temperature.
 
What a difference this made, completly feels like a new car

Wish i checked my car with a vagcom when i first got it
 
whereabouts in the engine bay is when you look at it with bonnet up?:think:
 
no gonna try and get my brother to have a look at hes a bit morew technically minded than me
 
Got the part from audi, £22 plus vat

you have to take the plastic engine conver off

then on the right hand side you will see a wire going into the temp sensor, need to pull a clip out then change the sensor

but make sure you open the coolant bottle up,
 
Rick do you have to keep the coolant cap off throughout changing the sensor? or just take it off before you start and then put it back on before starting?
 
audi upgrades
I took it off, but still lost alot of coolant, but then i put cap back on and the coolant stoped squirting out if that makes sense

so what i was, open it, and close it striaght away then remove temp sensor (hopefully it should stop the coolant suirting out)
 
Yes you have to take the cap off to release any pressure, then put it back on so that air can't get back into the system. This prevents the whole of the expansion tank emptying itself via the coolant sensor.
 
cheers, looking at many posts on here it says changing the coolant temp sensor will solve my occasional starting probs? or do i have to change another sensor?
 
It's a common failure and can cause all sorts of wierd issues, depending on the fault. Mine caused my car to stall when the engine was cold, I couldn't believe the difference just by changing this £20 part. It can also cause just rough idle, high fuel consumption etc really depends if it's telling ECU the engine is hot when it's cold or telling it it's cold when its not.
 
AndyMac said:
It's a common failure and can cause all sorts of wierd issues, depending on the fault. Mine caused my car to stall when the engine was cold, I couldn't believe the difference just by changing this £20 part. It can also cause just rough idle, high fuel consumption etc really depends if it's telling ECU the engine is hot when it's cold or telling it it's cold when its not.
Click to expand...

your 100% spot on there mate, my car feels like its been mapped just by changing this part :)
 
jojo said:
You've obviously never driven a mapped S3 Rik. :moa:
Click to expand...

lol your coments always make me laugh

well it will be mapped soon, then we shall meet next year at GTI International - Deal
 
jojo said:
I will be up for it mate, if I still have the S3. :racer:

Time for some :asskicking:
Click to expand...

Come on you know you want to keep it, You still got a load of mods to do to the car

What would you like next ?
 
rickparmar said:
Come on you know you want to keep it, You still got a load of mods to do to the car
Click to expand...
That's the thing Rik, I've not got round to fitting everything because 1. I havn't had the time, and 2. Maybe I'm actually bored of the car, despite the fact it ticks a lot of the boxes.

What would you like next ?
Click to expand...

Something more track focussed?, something with 300BHP minimum!


I think I have done something like 2500 miles in the last 10 months in my S3, which makes it an official weekend car, so might aswell buy something a bit more raw I can have some fun in.
 
you should get a BMW M3, and leave the S3 as your main weekend car,

Whats the millege now on the car ?
 
nik patel said:
Rick i dont have VAG.COM. How longs does it take to change roughy? and how much is the part?
Click to expand...

took me bout 5 mins, lol

no tools needed and part is £22 plus vat
 
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