2.5Tdi coolant temp sensor faulty?

[wid77]

I've got a few queries with my 2001 A4 which might be related.

1. I'm not sure my engine is giving it's best but as I have only had the car a short while and not driven another 2.5Tdi I may be wrong. It feels as though the power has to be 'wrung' out of it a bit. There's not a lot of torque low down but if you put your foot down it will pull well once past about 2000rpm. I'm used to a 115PD engine so this may just be the difference between a V6 and an inline four as it has more parts to get moving if you see what I mean.

2. The needle on the temperature gauge doesn't move from it's cold position not even after a few hours of driving. My old 1.9 was similar in this respect but it did at least move a little bit. It has been cold recently but I would still expect to see some movement.

3. The car takes a second or two to start but start it does. The last few mornings I have then had the red temperature warning flash up but after a minute or so it then goes out and doesn't come on again all day. I've read this could be a faulty level sensor in the coolant reservoir so I'll check that.

So, does anyone think the above are linked at all? I'm giving the car a service later today so I thought it might be a good idea to change the coolant temp sensor but I'm also wondering whether the thermostat may be faulty? Thanks for your help.


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[wid77]

My plans for servicing the car have been a bit if a wash out. The weather's blooming awful! Will look again tomorrow. So does anyone think I might be on the right track with the coolant temp sensor?


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[rya4]

Not sure about diesels but on my 1.8t the revs searched a little bit when temp sensor was gone and it did feel a little better after I fitted a new one. Never driven a 2.5tdi, but i'd imagine at 2000rpm the turbo would just be kicking in? I'd change all the filters, oil etc and the temp sensor and go from there.

[wid77]

Thanks for that. I've just ordered a Febi temp sensor off eBay. Under £14 delivered instead of nearly £40 from Audi. I hope it works! Will change that and give the car a service and take it from there. When I've got the basics sorted I'm thinking of a remap to give me a bit more torque. Always fancied getting it done with my 1.9 tdi as that engine died after the initial turbo surge had finished but I never got round to it. I'm not after huge gains just a nice smooth power delivery.


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[mikeybutch]

These are a bit special and it would really help to get a diagnostic check for any faults.I assume its a 2wd manual and I have only driven quattros but there s/b loads of low down torque although they are not that quick to take off.Could be the CTS or maybe the stat has failed but it should get to 90 quickly and stay there.Has it had a belt change if so were the stat and pump changed.Timing isn't easy and that could need doing and that could improve starting and performance.Temp warning is odd and wouldn't be the level sensor.Does the heater work well?if not could be the stat stuck

[wid77]

Thanks for the comments. It doesn't show any movement on the temp gauge and does seem to lack a bit low down but plenty of power when the revs rise. The MoT is due soon so I'm going to take it to an audi independent I use so they can give it a check over. I'll change the cts in the meantime and see if that improves anything. The heater does blow warm air after a few miles so not sure if it's the stat or not. It had a cambelt change about 20k miles ago but that was 3 and a half years ago so I will get the belts done at some point and I can then get the water pump and stat done too. Am I right in saying the fuel pump
also has to be timed? Does anyone know if that can be done at any time or does it have to be done when the timing belt is done? I'll ask the garage to check this too if possible.

I do like the car and feels a bit more special than my old 1.9 115PD. I'm getting about 34mpg mostly short journeys so pleased with that as I have been trying it out a bit .


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[kite]

Unplug the cts and see if starting improves.
The 2.5 is a bit slow away from standstill but once rolling it can be deceptively agile.
I quite enjoy playing with the big boys in lane 3....

bloody smart phones....

[mikeybutch]

I suggest you check the receipt and if it doesn't include the stat assume it wasn't changed which happens .Then if you have a look after it begins to warm and see if you can tell if its only the engine or if the rads warm too the the stats open and needs replacing which means belts time too.I find my heater is very effective and gauge is soon on 90.If the cts has gone she wouldn't run or start well

[wid77]

I'm just waiting for the temp sensor to arrive so should know this week of that sorts it.

I've also realised the oil temp gauge doesn't move either. Not sure if that's the same problem or if it's due to the cold weather or not? I might need to find out where this sensor is too and check it.


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[wid77]

Well I've changed the coolant temp sensor and so far my temp gauge has not moved a jot! Still not got any movement out of the oil temp gauge either. The heater does seem to blow warm air too so I am pretty confused still.


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