Temperamental temp gauge

[Mbr1992]

Hi!

 

i have an Audi A4 B6 avant 1.9tdi and my temperature gauge is going haywire for the past 2 months, took it into a garage and they had it 3 days and said they can't replicate the problem (that was a lovely £200 bill for losing 2 days of work) but I have days where it doesn't happen and days where it happens every minute of my 30 mile commute 🙄 

I have a feeling it might be the temperature sensor due to the fact that when I turn my ignition on and not my engine it goes straight up to 130 degrees which is impossible due to it being sat in temperatures floating around zero for over 12 hours between each working day. 

When im driving some days it won't move from the 50 degree mark for the whole 30 mile journey, some days it will be flicking between 50 and 90 but when I accelerate hard it will go up to its normal operating temperature of 90 degrees and on the odd occasion it will flick really quick between 50 and 130 degrees. 

I also get the annoying red coolant notification on my dash every few minutes, I've used a code reader on it and didn't show any codes and the garage did a diagnostic and they also said nothing was showing.

Any my ideas on what it could be?

 

Thanks 

[Trevor]

Hi Matthew....welcome to the Forum

I would advise to check that the coolant is not running low or overheating at any point but if not then I would definitely suspect the coolant temperature sensor or the wiring.

I have found the wiring going into the plug attached to the sensor to be the problem a lot of the time so worth checking this first, if not the replace the sensor.

Keep us updated on the outcome.

Cheers  Trevor

[Mbr1992]

Hi Trevor,

 

thanks for your reply, 

I actually had an oil leak a while ago that was directly above where the sensor and wiring sit, I've ordered a new sensor to try and replace that and see if that's the problem but I'll check the wiring for any signs of oil/dirt. 

Coolant levels just under the maximum and I'm not losing any I don't think.

Garage said that when they checked it the gauge was showing the correct temperature for the coolant but it's so random it's hard to get it to a garage when it's happening, I came off the motorway early last week because it had done it all the way home and pulled up outside the garage and it stopped doing it haha.

is there any way of checking coolant temperature myself? Can I literally just use a thermometer probe straight into the  coolant cap? I have a code reader but it doesn't show the coolant or oil temperature. 

 

Cheers

Matthew

 

[Trevor]

I always use an Infra-Red Temperature Gun  

http://www.ebay.co.uk/itm/Handheld-Non-Contact-IR-Laser-Infrared-Digital-Temperature-Gun-Thermometer-/172527792934?hash=item282b753326:g:uvYAAOSw4CFYn~2I

Measure all around the engine for temperature hotspots, etc.

Also useful to measure misfires, brake efficiency/balance, and a whole host of other useful stuff

 

[Mbr1992]

Hoorah! I replaced the temperature sensor this evening and went for a drive and had no problems whatsoever, I'll see how it fairs on the commute to work tomorrow.

 

ripped my arm to shreds getting the plug off the back of the sensor though, it was caked in coolant, also inside the plug was full of dried coolant and the o-ring was ripped too. I cleaned the plug out, replaced the sensor and its hopefully sorted now.

photos of older sensor attached.

 

many thanks

 

matthew 

[Trevor]

I think they call that 'a job well done!'