Overtemp Warning

[Pythix]

Hi all,

On the more colder mornings, when I start the car, the overtemp dash light comes on immediately. It will stay on until I switch off and then back on again. On some of the more average mornings it doesn't happen.

Am I lead to believe that these sensors can get so cold that they think it's hot????

Any ideas??? New sensor needed??

TIA

[robmawer]

Yeah, will probably just be a new sensor (was on mine when it did that). IIRC it's the one which sits in the "coolant reservoir" to the left of the engine...

Rob.

[boyced]

think you need to replace the whole coolant reservoir, as the sensor is part of that. Mine has also sarted to do it!

[robmawer]

think you need to replace the whole coolant reservoir, as the sensor is part of that. Mine has also sarted to do it!

Now you mention it, I think you're right...can't believe it was only March they did mine and I can't remember what it involved...

Rob.

[Pimpster]

Is it expensive to replace?

[stopan1j]

My Octavia RS has also just started to do it on freezing mornings also- seems a bit common:rolleyes:

I think the part no for expansion tank with sensor incorporated is part no 1J0 121 403B and if my search is correct is available from euro parts, part no 205440420 at £7.99 + vat and postage if required. Not sure now much the part is from Skoda or VW, although the europart shows as original

No gaurentees with details I have posted

[The Skud]

Had mine done at about 40K under warranty, the whole reservoir needs to be replaced, quick and easy job though, I think that the latest version of the reservoir is supposed to have a green sensor on it, although someone may corrcet me on that:rolleyes:

[robmawer]

Is it expensive to replace?

Think it was about a ton to get fixed...can't remember, had some other stuff fixed at the same time...

Rob.

[TaviaRS]

Mine was just a new sensor, not whole unit.

Had a total of 3 in the course of 140k miles on the RS

[DGW]

I think the part no for expansion tank with sensor incorporated is part no 1J0 121 403B and if my search is correct is available from euro parts, part no 205440420 at

[stopan1j]

[Stuart_J]

Both our Octys started doing it in the cold weather, must be a very common problem

[stopan1j]

OK been to VW dealer and purchased the coolant tank part no 1J0121403B the cost was 8.53+vat level sensor (2 long probes) is integral and cannot be changed seperatly its moulded into the tank. Also bought some G12 coolant to complete the task 5.67+vat for 1.5 ltr.

Not sure if this will solve the problem or if its the engine temp sensor as I believe is what TaviaRS had changed.

Will change and report back when fitted of findings - need cold weather again to check.

[stopan1j]

Ok tank now fitted seems to have cured the problem. I started the car from cold before replacing and the temp /level audible and visual warnings were output. Changed unit - restarted no warnings.

Instructions detailing how I replaced the unit :-

Time required 20-30mins

Tools required:-

1J0 121 403B replacement coolant tank VW/Seat/Skoda dealer (VW dealer price 8.53+vat )

Phillips screwdriver

Mole Grips or large pliers

Small amount of G12 antifreeze from VW/Seat/Skoda dealer (VW dealer price 5.67+vat for 1.5 ltr)

Blanket or Polythene Sheet (desirable)

Empty container - an old screen wash bottle is ideal

Bottle of Beer

1. Remove Watches and any rings on hands for safety for you and car paintwork

2. Open Bonnet - Ensure engine/coolant is cool

3. Place Blanket or protestive polythene sheet over drivers side wing to prevent antifreeze and tool marks

4. Locate Coolant tank - will look same as replacement - check before removing

5. Remove sensor cable from top of tank and unclip cable from tank body together with another cable next to it.

6. Remove 2 fixing Phillips fixing screws and store safely.

7. Locate the small hose on top of tank - compress clip with mole grips and slide along hose so it clears the tank pipe it is gripping. Pull off hose a small flat screwdiver may be needed to ease the hose away from the tank pipe.

8.Ease away tank so bottom larger hose can be located - again compress clip with mole grips and slide along hose so it clears the tank pipe it is gripping. Pull off hose, a small flat screwdiver may be needed to ease the hose away from the tank pipe. put finger over bottom tank pipe as you remove to prevent fluid draining away.

9. Empty tank into the empty container you have.

10. Refit replacement tank - reversing the steps above.

11. Pour a small amout of G12 antifreeze into tank up to about the min mark - top up to max mark with the saved fluid in your container. (I chose to dilute with this old mixture - if using water use distilled water)

12. Remove wing protection and any tools from engine bay

13. Start engine, check warning lights, switch off, check for leaks.

14. Recheck coolant level

15. If alls OK or not drink the bottle of beer - do not drive after:thumbup:

[Pimpster]

That's brilliant mate. Will try it this week, if all goes well, will let you know

[DGW]

A very nice write-up!

[stopan1j]

Thanks DGW and Pimster its apreciated - It makes making the effort worthwhile