Car drives fine, and temp gauge sits precisely where it should, with no issues.

Yet on start up, I get an alarm, drawing attention to red temp gauge warning light on screen.

This has happened last few days, and light clears straight away once switch off and re-start.

Not so today, Stayed on regardless, and whilst driving. Drove a mile, switched off, started again, light and alarm gone.

Car serviced yesterday, and as a sidelight bulb was out, they figured this was related. Not so !.

Any ideas ?

Hoping for a faulty sensor at most !

Thanks very much

Seem to have create a duplicate post in error when amended title of this one.

Please reply to this, and ignore previous

Thank you

Have you checked the level in the coolant header tank?

If it's on MAX then unscrew the lid and take a look inside. There are two metal prongs on the surface, do they look clean or are they furred up?

Check there is no oil in there either!

The garage reckoned a blown side light bulb could be related to the coolant warning light?

I wouldn't be taking it there again!

Thanks.

Yep, it is up to max cold in coolant header tank.Definitely no oil in there !

Will check out prongs tomorrow when stops raining. Thanks for suggestion

The garage reckoned a blown side light bulb could be related to the coolant warning light?

I wouldn't be taking it there again!

Seeing as car was only in for service, they didn't take this issue any further.

Just suggested odd things happen (but not designed to do that) when one warning light appears - i.e bulb warning light which was on. Also suggested sensor, dash fault etc if intermittent and all else behaving ok,

To be fair a failing battery has been known to cause some weird faults on the Octavia.

A blown bulb throwing on the coolant light is a little extreme though!

Without checking the manual is there different lights / colours for the coolant?

For example, red for coolant too hot, amber for coolant too low etc?

If the light is signaling the coolant is too hot then may be the thermostat is faulty, they are known to not last forever...

Thanks. Good starting point for problem solving tomorrow.

No huge concerns at present, as intermittent, and car drives & behaves 100%.

My money is currently on sensor then thermostat !

Just checked the manual, a flashing coolant light can mean one of two things...

1) Coolant too hot.

2) Coolant level too low.

On a cold start and after checking the levels you can rule out either of these two scenario's therefore suggesting a genuine fault.

I reckon you are heading in the right direction by checking the sensor and themostat...

Aye, just read that in manual too last few minutes.

1/ Definitely not too hot on a cold start !

2/ Definitely not to low when maximum at cold start

cheers for your input.

Had exactly the same problem. Give the probes in the expansion tank a clean up with a clean tooth brush fixed mine

John

Thanks for the tip. Tried that to no avail, so replacing the sensor next - thats if it can be removed from expansion tank. Think it must be as there's lots of expansion tank on sale, with no mention of a sensor.

I think it's just as easy to replace the expansion tank that try to replace the sensor inside the expansion tank...

Tool a look at ebay, where expansion tanks and sensor's sold individually.

Better sources of info when all back at work tomorrow

Sensor prongs caked in stuff that was stayed untouched by toothbrush and small wire brush.

So, took header tank off, and left mix of coca cola & Bicarbonate of soda to soak overnight.

Sorted. Clean sensor prongs, and no repeat of the warning light.

Thanks for your advice folks.

Thanks for the update, did you have to drain the coolant to remove the header tank?

Figured it was easier to drain and remove, as bottom hose removal would loose quite a bit, and had none to top it up with.

Refilled, started, no problem since, and no need to bleed for such a tiny amount of air introduced to top of bottom hose on refill.

Skodaparts only wanted £17 and delivery for new header tank including sensor. Skoda main dealer wanted about £38 for sensor alone.

Hi, I know this isn't new topic. However I have a same problem with my warning light and alarm.

 

It began with my temperature sensor going mad. Sometime it dropped from 90 degrees to 0 in seconds while engine hot. Before I had a chance to replace it another fault popped out. The warning alarm with red light (coolant sensor). So I have replaced the temperature sensor, topped up my antifreeze and problem was gone for about a week.

 

Now I have no problem with my coolant temperature sensor, but the fault of sounding alarm and red light is back. I have tried everything described above apart from replacing the expansion tank or thermostat.

 

What would you do first? Replace expansion tank or thermostat or replacing both?  

 

Thanks any suggestions 

 

 

I just realised that I am in Octy2 forum. My car is however Octavia MK1

Edited 18 January, 201412 yr by kasino