I would appreciate any advice on the following problem on my Y reg Fabia SDI.

From starting the engine, the needle/guage appears to be working normally ie climbing from left to right and settles at the vertical position. It never used to move from that position regardless of road and traffic conditions.

However, after reaching vertical and settling at that point, it now drops back towards the left. It settles at various points between vertical and the mark midway between cold and vertical

I am not a techie but given that the coolant level is ok and I can find no other problems, I suspect that either the guague itself or a sensor providing it with the information is faulty.

Your thoughts would be appreciated as to cause, solution and likely cost.

thanks in advance

Martyn

Hi Mate

I would say coolant temp sensor.

They do suffer with these.

Easy cheap fix , so could be replacing that to start

Hope this helps

Sarah

Sarah - thank you for such a quicky reply.

No worries mate.

Easily done yourself too.

Do you know your way round the engine?

I have known someone be quoted £100.00 + VAT for this job and it is quite easy to do when you find the sensor.

It is located on the thermostat housing.

Sarah

I always assumed this happened because a diesel engine is thermally efficient and I noticed this behaviour on my old Fabia TDI (ie in the winter you could sit stationary in a traffic jam and watch the needle drop).... Under what conditions is the needle dropping? If it's when the engine is being worked hard, I'd say there is a problem but if it's cruising/idling I wouldn't worry

Chris

Hello Sarah

Other than checking the oil, coolant, brake fluid and windscreen washer fluids, I am a complete dummy when it comes to what's under the bonnet.

Unless the sensor is a simple push on fitting without needing to unscrew/unbolt parts of the engine, I will probably have to pay a garage. I don't even know where in the engine to look for it. Unless it is marked in big letters in luminous paint I will probably never find it!

Haynes' manuals may be great for mechanics but no good for dummies like me!

thanks again for your advice

Martyn

Hello Chris

It is dropping when cruising on a motorway and in town driving. It never used to move so it seems odd that it now drops

Martyn

Mine when reaches temp does not move at all idleing or moving it does not move

I have the 100PD one

So I would think that it is reading incorrectly.

I am sure there is a how to guide on this.

Check out the Fabia section on here as I think it could be there

Sarah

Sounds more like a thermostat stuck open to me. I've had it on two, or three, different cars. Temp drops at idle and in slow moving traffic and the heater output falls off.

Unless the sensor is a simple push on fitting without needing to unscrew/unbolt parts of the engine

It more or less is. With the engine cold unscrew the tank cap, squeeze and hold the top radiator hose and screw the cap back on (this creates a little vacuum in the system to prevent coolant loss). Disconnect the sensor electrical plug (pull the tag and simultaneously push the connection onto the sensor and then pull it off), remove the sensor clip, pull the sensor out, retreive the rubber seal, either re-use or replace onto the new sensor, push the sensor into its' housing and re-fit the clip and plug. Unscrew the cap to sort the pressure out and screw it back up - also check the coolant level.

It more or less is. With the engine cold unscrew the tank cap, squeeze and hold the top radiator hose and screw the cap back on (this creates a little vacuum in the system to prevent coolant loss). Disconnect the sensor electrical plug (pull the tag and simultaneously push the connection onto the sensor and then pull it off), remove the sensor clip, pull the sensor out, retreive the rubber seal, either re-use or replace onto the new sensor, push the sensor into its' housing and re-fit the clip and plug. Unscrew the cap to sort the pressure out and screw it back up - also check the coolant level.

There you have it , it IS that simple.

Sarah

sounds simple enough for even a dummy like me!

Many thanks to all of you for your advice

Martyn

Had this problem with my Octavia (2002 Elegance TDI MK1 110BHP). Engine would warm up to normal temp then guage would just drop then go back to normal after a few mins. Got it serviced a few weeks back and the VAG-COM picked up an error on the coolant temp sensor, so they swapped it (although it doesn't look new to me, probably just twiddled with it until the code wasn't produced). Try just pulling the sensor connector off and checking the contacts. The sensor is located on the side of the coolant reservoir and just pulls of I think (there maybe a clip if I remember correctly). Haven't had any issues with it since.

sounds simple enough for even a dummy like me!

Many thanks to all of you for your advice

Martyn

I did a guide here. Covers most of what you need, but you'll need to make use of fordfan's advice unless you fancy draining the entire thing!

HTH

it also sounds like a faulty thermostat to me

I did a guide here. Covers most of what you need, but you'll need to make use of fordfan's advice unless you fancy draining the entire thing!

HTH

Dont scare the guy ap0gee, thats your guide for the evaporator temp sensor.

Heres the coolant temp sensor one http://www.briskoda.net/forums/technical-guides/fabia-coolant-temp-sensor-how/66180/?highlight=coolant+temperature+sensor