Engine temp gauge

[Butcher]

Something seems a bit wrong with the temperature gauge on my car - it seems to read low or something. Basically it alwys reads cold unless I'm ragging it down the motorway, then it mightn get up to 80-90C, but as soon as I slow down below about 60 mph it drops right back down to cold again. I'm fairly sure that car egines should stay up to temp once there so I'm guessing something's awry. Car seems to run fine regardless and it's not guzzling fuel or anything.

Question is, is it just a dodgy sensor? If so is it worth worrying about or leave till service? Or is it a symptom of something else?

[GoNz0]

nah i doubt very much its a dodgy sensor, you gave the perfect signs of a thermostat thats stuck open. all it will do it throw your economy off a little as it remaps the fuel, come winter i doubt it will move off the cold zone, should be an easy enough job if your any good at motor DIY, would take me about half hour to an hour, so give yourself a couple of hours, and get a gallon of anti-freeze and change it out while your at it. your going to lose a litre or 2 when you remove the thermostat housing, so may as well do it all !

[Konan555]

all it will do it throw your economy off a little as it remaps the fuel

...and take longer for the oil to get up to tempreature

It throws the economy off a mile on start up because it's in cold-start for longer as well.

[Butcher]

Well I mainly use it for commuting to work (at present about 45 miles each way) so it doesn't spend much time in cold start I guess. ;p

Will see about getting a new thermostat for it.

[Neo_VR]

Not to mention your heater just wont heat up in winter...

[oshta]

Just ring them up, arange to take it in and get a new stat fitted, shouldnd be too stressfull!


Daniel

[Butcher]

Funnily enough the heater does actually work...

[Moby-Dick]

it could be a dodgy temp gauge.

The Nissan ones are a little bit like a small child doing hide and seek....

1,2.....99,100 !

if you dont mind wirign one in , why not invest in a seperate water temp gauge.

[Butcher]

Well it's not a nissan (Audi A3 as it happens).
Rather just get the one I have working.

[GoNz0]

Funnily enough the heater does actually work...

it will, but not as much as you hope for come a freezing winters day !

if its a dodgy temp guage, it wouldnt go up to normal when he is flooring it down the motorway.

[5lab]

temp gauges/sensors are NOT a calibrated science - so much so that most modern cars have voltage stabilizers to force the needle into the middle when driving, so you don't get alarmed.

your symptoms point to 4 things, imo, in order of likelyhood (again, imo)

1. thermostat. as it goes up on the motorway - a properly functioning car would hold the same engine temp from 0-100 mph, so even if the gauge were dodgy, it'd point to the same place all the time
2. sensor
3. gauge
4. voltage stabilizer

there are ways to test the thermostat (stick em in a pan with a thermometer, turn the heat up, find out what temp it starts/finishes opening), after that, just live with it, imo