Temperature gauge taking a while to get to the middle?

[SeanyK]

Hey folks, I know it's cold weather outside and all that, so it's going to take longer for the car coolant to warm up, however, i've noticed the last few days (it may have been happening longer but only just noticed).

When driving in the morning, from cold, gently driving the car temp gauge makes its way up slowly... When it gets to about 1/4 or just past it, it basically stays there for ages, im convinced i've seen it go past it, then back down again a few moments later? And it will eventually get to the middle and stay there (perhaps 15 minutes or more after?) This is driving at a constant speed, and also stop/start heavy traffic driving.

The only thing I can think of are;

1) Coolant temp sensor (but VCDS scan does not show faults)

2) Sticking thermostat

3) I had my Cambelt & Water pump changed @ VW in August... So I can't see it being the water pump... But you never know?

Any ideas?

[RENNTAG]

my mk4 golf had a similar issue to this,
would gain som temperatue then drop back down a bit.
trned out it was the coolant temperature sensor.
did not show a ault code for it though, just replaced the sensor.

[ub7rm]

Mine does exactly this in cold weather, nothing to worry about if its a fairly short journey.

1st ten minutes for me is through town at 30 mph / traffic etc and it will warm up to about 45 deg on the gauge.  Then when I hit the dual carriage way it drops a little from this but has risen a bit by the time I get to work (another 10 mins ish on the dual carriage way).

Last winter I travelled about 50 miles through temperatures ranging from -5 to -15 and even over that distance it didn't warm up properly ...

[SeanyK]

That sounds exactly like my drive to work... Around 40mph for about 5 minutes, then stop start through a village at about 20mpg, then onto a dual carriageway for 5-10 mins, by the time I get to end of the journey (approx 20 mins) the temp gauge is firmly in the middle.

[Teutonic_Tamer]

Engine coolant temperature sensor.  Common-ish problem.  £20ish for the part - plus labour to fix.

All you sufferers really need to get it changed - because the 'apparent' low temp reading from the ECT will cause the ECU to constantly over-fuel - and possibly damage your cat.

[Kalpsn2000]

Engine coolant temperature sensor.  Common-ish problem.  £20ish for the part - plus labour to fix.

All you sufferers really need to get it changed - because the 'apparent' low temp reading from the ECT will cause the ECU to constantly over-fuel - and possibly damage your cat.

So out of interest, should the temp needle be in the middle pretty quickly? Approx time?

[Teutonic_Tamer]

How long is a piece of string?  There are way too many variables to give a definative answer - but basically, the needle should rise in a linear, constant progressive manner.

[SeanyK]

I've changed a few of these on Golf MK4 1.8T's and previous Ibiza Cupra 1.8T's also, quite an easy job, so hopefully the MK5 GTI is similar!

I will find out the part number and post it on here for anyone interested,

Sean :)

[ub7rm]

Engine coolant temperature sensor.  Common-ish problem.  £20ish for the part - plus labour to fix.

All you sufferers really need to get it changed - because the 'apparent' low temp reading from the ECT will cause the ECU to constantly over-fuel - and possibly damage your cat.

Hmm interesting.  Is there one ECT or two?  In my case I'm not all that convinced its a problem.  In the summer the engine is up to temp quite quickly but in the winter it does take longer.  Which is what I would expect?

[Teutonic_Tamer]

Engine coolant temperature sensor.  Common-ish problem.  £20ish for the part - plus labour to fix.

All you sufferers really need to get it changed - because the 'apparent' low temp reading from the ECT will cause the ECU to constantly over-fuel - and possibly damage your cat.

Hmm interesting.  Is there one ECT or two?

There should be two.  One on the engine (usually on the cylinder head or near the thermostat), and one on the radiator.  The one on the engine has more effect on the engine ECU (for fueling, cat warm up, etc), and the one on the rad controls the coolant control module - basically provides info for the rad cooling fans.

In my case I'm not all that convinced its a problem.  In the summer the engine is up to temp quite quickly but in the winter it does take longer.  Which is what I would expect?

It is perfectly normal for the engine to warm up quicker in the summer compared to the winter.

But how are you gauging how the engine warms up - from the actual coolant gauge?  Another reliable way, if a little 'seat of the pants' method is how quickly the heater warms up.  This is most accurate if the climate control temp is set to 'HI'.

[SeanyK]

Looks like the part number needed is 06A 919 501 A

[SeanyK]

I changed this today folks, will see if it makes a difference, but the job itself is very easy! Easier than on the MK4 (& Ibiza Cupra's etc)!

It is located to the right of the engine block when looking down at the engine bay, facing the side of the battery.

Pop retaining clip off with flathead screwdriver, pull sensor out, take old O-Ring out, replace O-Ring & Sensor, put back retaining clip.

...And put some coolant back in to cover what just flew out! 

Do not do this job when the engine is warm!!!

[ub7rm]

I changed this today folks, will see if it makes a difference, but the job itself is very easy! Easier than on the MK4 (& Ibiza Cupra's etc)!

It is located to the right of the engine block when looking down at the engine bay, facing the side of the battery.

Pop retaining clip off with flathead screwdriver, pull sensor out, take old O-Ring out, replace O-Ring & Sensor, put back retaining clip.

...And put some coolant back in to cover what just flew out! 

Do not do this job when the engine is warm!!!

Any feedback on this?  Starting to wonder now if its not so 'normal' for me.  I'm finding the car a bit sluggish to start from cold these days and it doesn't hold the revs up for a couple of minutes like it used to either.  Wondering if this is all temp sensor related...

[Richn83]

Any feedback on this?  Starting to wonder now if its not so 'normal' for me.  I'm finding the car a bit sluggish to start from cold these days and it doesn't hold the revs up for a couple of minutes like it used to either.  Wondering if this is all temp sensor related...

Interested in the quicker drop in engine revs at cold start, ive noticed mine do the same since the temp dropped.  Would be interested to know if anyone else has had this sympton, havent scanned the car yet maybe I will do a quick one tonight.

[SeanyK]

Hey folks, well it doesn't go to the middle and back down again etc anymore!

It's a very easy job to do so i'd change it if I were you just to rule it out :)