Quest: 05 1.8t awd-Fans turn on at startup?

[honinspire02]

ok well i noticed over the past few days when i start my car in the morning the fans turn on full blast till the temp gauge gets about halfway to normal... Is this normal? what gets me is its cold in the morning and the fans turn on so ont see why fans should turn on..? any feedback will be greatly appreciated thanks

[EBG 18T]

i had an intermintant problem with the fans kicking on like that and eventually it lead to cooling issues. You can check the green top sensor (ect) and then the thermostat. The green top is cheap ~$10 and for some reason seems to fail pretty often.

[MikTip]

Might be the a/c high pressure switch...

Is you a/c on?

[jleves61]

I just had this same problem. The fans would turn when the engine was cold.

It was indeed the engine coolant temperature sensor, a fairly easy fix. If you scan the car you should find the fault.

[honinspire02]

Might be the a/c high pressure switch...

Is you a/c on?

no not at all.... climate control is completely off...

[2003Qu4ttr0]

OK, now this is just getting ridiculous. My rear coolant flange couldn't take it anymore and kicked the bucket. I had it towed to the shop for repairs. This was last August. While in shop the flange was replaced along with a brand spanking new ECT switch. Awesome. Lo and behold a few weeks later, my car starts misbehaving; loud assed engine fan on startup and CEL. What the heck!? I know you gotta pay to play, but this is stupid man.

.....my '04 Hyundai Accent was better than this. Sad.

[2003Qu4ttr0]

^^Sorry, just had to vent. It's been love/hate with this car. I hope someone can enlighten me. I don't feel like sticking my hand in that armpit of a space between the firewall and the sensor. Did I also mention it's -27 Celsius here. It's damn cold and don't want to DIY anytime soon.

[old guy]

Before you can diagnose a problem with the cooling system it helps to have a better understanding of how everything is tied together. This may help a little: (Copied from a MikTip post on AW from several years ago. Thanks Mike!)

Engine Coolant Temperature (ECT)
Sensor G62 and Engine Coolant
Temperature (ECT) Sensor
(On Radiator) G83

These sensors both operate as negative
temperature coefficient (NTC) sensors. The
coolant temperature set points are stored in
the Motronic Engine Control Module J220
in the form of maps.

The actual coolant temperature values
are registered at two different points in
the cooling circuit and indicated to the
Motronic Engine Control Module J220 in
the form of a voltage signal.

* Coolant actual value 1 is measured at
the cylinder head coolant outlet by
Engine Coolant Temperature (ECT)
Sensor G62 located in the upper level of
the coolant distributor housing.
* Coolant actual value 2 is measured at
the radiator by Engine Coolant
Temperature (ECT) Sensor (On Radiator)
G83 before the radiator coolant outlet.

Signal Utilization

Comparison of the specified temperatures
stored in the maps with the coolant actual
value 1 temperature gives the pulse-widthmodulated signal for the application of
voltage to the heating resistor in the Map
Controlled Engine Cooling Thermostat F265.
Comparison of the coolant actual values
1 and 2 is the basis for activation of
the electric Coolant Fan V7 and Coolant
Fan -2- V177.

Effects of Failure

If Engine Coolant Temperature (ECT)
Sensor G62 fails, a defined substitute value
of 203°F (95°C) is used for coolant
temperature control and the first fan speed
stays activated.

If Engine Coolant Temperature (ECT)
Sensor (On Radiator) G83 fails, the control
function remains active and the first fan
speed stays activated.

If a certain temperature threshold is
exceeded, the second fan speed is
activated.

If both sensors fail, maximum voltage is
applied to the heating resistor in the Map
Controlled Engine Cooling Thermostat F265
and the second fan speed stays activated"

[honinspire02]

as far as scanning goes can they do that at autozone? or do i have to go to a speciality shop?

[honinspire02]

as far as scanning goes can they do that at autozone? or do i have to go to a speciality shop?

up

[EBG 18T]

as far as scanning goes can they do that at autozone? or do i have to go to a speciality shop?

you can try autozone. they have the generic tool. if you plan on keeping the car for a while a vagcom would be a wise investment. it is vag specefic. i have both and vagcom & vad tool and they are very handy to have.

[jackitorslamit]

I had this same issue and a CEL popped up. Went to Autozone who gave me a general code. Went online and ran the code. It ended up being the coolant temp sensor. Which you can get at Autozone sometimes for $6 (no o-ring or clip: just don't break yours). It is a simple fix, but a pain in the butt to get to the sensor. Had to get my girlfriend to help reach the clip I dropped TWICE in the motor.

[honinspire02]

ok got my car scanned at autozone code p2181 came back something about cooling system performance... I'm bitching out the dealer tomorrow cause they told me right before my warranty ended last week that it was normal...

[JMRQuattro]

Both of my fans turn on on start up too. But i don't think it's because i have any failed sensors as i have no CEL for it. My engine codes were for cylinder 2 misfire and SAI incorrect flow. Soooo wtf?

[festerfm]

same thing.... no cel, both fans on full blast, and just today changed the green top sensor... pullin hair out!!

[festerfm]

well, she seems good now.. i changed the sensor yesterday and i started it right after and sure as shit, fans came on... i was pissed... figured i'd just deal w/ it another time. i had no cel but i decided to scan it anyways just in case and came up w/ a SAI code, somethin that had nothin to do w/ the coolant temp sensor, so i cleared the code and drove to my bowling nite... started the car after bowling, and the fans stopped... cant tell ya how pleased i am.. i'm actually happy!!! now i just need to top off my coolant since my light came on yesterday. i thought if you popped the top on u'r coolant system and released the pressure, that it would keep coolant from spilling out the hole... well i lost about a half gallon of fluid.. i need to find out if i can put any coolant in there or if like everything else, it has to be a certain audi stuff.. if so, i'll prob just add some water to it since no audi place is open around here on saturdays.

again, if u'r going to do that sensor on u'r own, go to audi b4 and get a new clip and o-ring... will save some aggravation... it's also pretty handy to have a telescopic mirror handy...