Temp Gauge Fluctuation

[Tyler]

Hi guys,

Just a quick question about my temp gauge in my Mk4 GTI. It has been acting really odd lately. It will go up and down quicker then i can shift gears haha.

For example i went for a 14km drive into the city. On the way in the temp gauge worked like normal and went to half way.

Roughly half way home i noticed the temp gauge was down to dead cold thought this wasn't right so i drove around trying to get the temp gauge up at bit. it did but still not to half way, then by the time i got home. Pic below



Now i took it to my mechanic to get checked out, he thinks it fine but i still dont think its right, he also said he gave the car a scan and nothing showed up.

Its cold in canberra at the moment but would this make the temp gauge fluctuate so much?

[blutopless2]

temp gauge should be dead steady once the engine is up to temp.. my cars all run at 90 deg on the dot.
not sure where your temp sensor is but things i can think of that might make it jump around would be bad connection, depending upon the location of the sensor if it is in and out of the water - like you've got a low level or an air pocket etc...
in my experience with temp sensors they usually work or they dont... usually an external reason for fluctuations.

[Tyler]

Yeah thats what i was thinking, think i might take it back to the mechanics and try and get it sorted out

[dainese]

i reckon thermostat. it is meant to get up to operating temp as soon as possible and maintain it. if it gets too cold, thermostat will close and stop circulation thru system(radiator inc)

[dainese]

It does go up and down and for example one trip it will reach temp like normal and others it wont move at all.

could it be the senderunit?

heaters work fine and heat up within a couple of mins driving

hmm. heaters are a good indication of some temp in coolant - thermostat is working in one way or another.

sender? as in temp sensor? it shouldn't fluctuate. as the other member said, they ususally fail...

[dainese]

For example i went and filled up today at the petrol station, when i pulled in it was about a third, after filling up and paying i turned the car back on it went straight to half but after 5-10mins it went down to stone cold.

My old man thinks its the sender unit? i will be ringing up again and getting the car booked in during the week hopefully

describe the fluctuation and conditions when it does fluctuate.

im guessing its **** cold in ACT?

[Tyler]

Its actually fairly nice at the moment.. 13 degrees, 16 tomorrow etc etc certainly not cold enough to effect the temp sensor in the car...

I will get my mechanic to have a look at it during the week hopefully and solve the problem

fluctuation is basically like i will be driving along watching it warm up slightly, continue driving and look down at the temp gauge and its back to stone cold... it will then start to warm up again then drop

[Dyldo]

i had this too matey when i bought my 4Mo about 6 months ago. It hasn't happened in months now though, but exact same symptoms and (very unscientifically) they went away on their own.

[xamispep]

I had this happen to my MkIV 1.6 recently. The gauge was fluctuating all over the place and taking an age to get any heat into her. I bought a new temp sensor and thermostat, flushed the coolant while i was at it and the little fella has been bang on 90 ever since, fuel economy has improved too

[dainese]

I had this happen to my MkIV 1.6 recently. The gauge was fluctuating all over the place and taking an age to get any heat into her. I bought a new temp sensor and thermostat, flushed the coolant while i was at it and the little fella has been bang on 90 ever since, fuel economy has improved too

sounds good. the thermostat is 'mechanical' and won't throw a code.

[craig_the_german]

My guess is the temp sensor.

There are a number of threads in here discussing the same issue.

[clark]

Where are you taking it to get looked at?

I would highly recommend the guys at Canberra VW Centre in Belconnen. I had an issue with my thermostat a month or so ago and they sorted it with no fuss.

[Tyler]

Its been to Canberra VW Centre in belconnen and its been booked back in for later on during the week. I got a feeling its the temp sensor as it works sometimes, and other times is doesnt even work.

I took the car on a 40min drive on saturday and the temp guage didnt even get to half way, got about a third up then decided to go stone cold

[Tyler]

Just got word back that the temp sensor has been replaced, thermostat looked alright so we should be back to normal

Thanks for the help guys much appreciated

[clark]

Just got word back that the temp sensor has been replaced, thermostat looked alright so we should be back to normal

Thanks for the help guys much appreciated

Glad to hear you got it sorted