Annoying Temp Fault

[AkAudiA4]

Hi all

I know that this is a much talked about topic in the past but i am struggling to find the right answer for my situation.

The situation...

My car recently through a solid Check Engine Light. The car starts fine, drives fine, idles fine, and as far as fuel economy goes its all business as usual. However the temp gauge does not move from the bottom 50 deg and from starting the car the fan blows like a leaf blower (at full speed). So i believed it was the temp sensor.

After reading posts i changed the temp sensor (green 4 pin) with a new one (exact same part number) however there seems to be no change to the temp gauge on the dash as it still sits on 50 deg. I've driven about 30 miles as i though it may need some time but no change apart from it rising slightly to about 65 deg and back down again?!

I have also checked the sensor is in correctly and sealed with no leaks as i did fit it myself and am far from an expert!!! Could there be another fault (a recent diags didn't pick up anything but the temp sensor - before swapping it), could the new sensor be faulty if so can i test this without paying for diags again, do i need to reset the ecu by disconnecting the battery or should it work from the go? or is it the thermostat?? All these questions an no idea :confused:

It is an Audi A4 2001 B6 1.8T. Please help!!!!!!

[coup80]

I had a similar problem of temperature wouldnt go above 70 it was the thermostat,the symptoms of the temp sender swith faulty is when your temp gauge is eratic,when i done my thermostat temp sat bang on 90 but now and again it would shoot down too 50 then back up to 90,then i done temp sender switch now bang on 90 all the time,

iam not sure why your fan is on all the time though,
do your heaters work?

[AkAudiA4]

Yeah my heaters work fine... i just let the climate do its thing but it hasn't had any issues to date. It does take longer to warm up but i thought that may be because the climate won't kick in until the temp rises on the dash (or in the ecu)... like i say though i was just guessing that was the case.

Would diags pick up a faulty thermostat? Also any ideas on a rough costing... had a look myself but the guides say you need to remove the alternator. I think temp sensor was my skill limit!

Thanks again for the help!

[benjie]

I don't know if this will help, but my fans went mental one day and it turned out my coolant temp sensor connector had popped off, so the car was receiving no info about the engine's temp, so the fans came on fast by default. Could your connection be a bit dodgy?

The fact the dash gauge doesn't move at all makes me think it's more likely to be the sensor. Give it a good clean and dry it well and see what happens.

Car won't pick up a dodgy thermostat, but it usually records a dodgy temp sensor.