Intermittent "low coolant" warning

[OmegaV6]

Hi all .. car is a 2014 Allroad with the 3.0 litre TDi (245 bhp) engine. in the past week it's started giving intermittent "low coolant - stop engine" warnings that last about 5-6 minutes then dissapear, only to come on again at some almost random time, although part of me thinks they come on more often going uphill and go out faster going downhill !!!!!!! A part of me also thinks the warnings only start once the engine reaches full operating temperature - on the gauge that is.

Level has, obviously been checked numerous times ... its halfway between MIN and MAX when stone cold ( 2°C last night ) and a fraction above MAX when fully up to temperature but with the warning ON !!

I don't have any access to a code reader.

Any ideas what the problem may be and what, if anything, I can do to resolve it please ???

Ta muchly

[Crasher]

Try it on max from cold.

[aaronvg]

I have had this problem in the past on my A6 and also on my wife’s A4 it was due to a problem with the sensor in the coolant tank. I believe the sensor is in the bottom of the tank. I had the tank replaced on both cars and the problem went away and has not returned since. It was annoying as the loud beep when the warning flashes up always made me jump the tank is not expensive to replace.

[OmegaV6]

Try it on max from cold.

many thanks .. will do ...

[OmegaV6]

I have had this problem in the past on my A6 and also on my wife’s A4 it was due to a problem with the sensor in the coolant tank. I believe the sensor is in the bottom of the tank. I had the tank replaced on both cars and the problem went away and has not returned since. It was annoying as the loud beep when the warning flashes up always made me jump the tank is not expensive to replace.

Thanks, I'll try crasher's idea first !

[OmegaV6]

Unfortunately upping the level as Crashers suggests makes little difference, drive up a hill and the warning comes on .. level off or downhill and out it goes !! looks like a replacement header tank needed as I can't see the sensor being replaceable. Any one know a part number and/or reasonable source please.... and what is the recommended anti freeze for these beasts ?

Regards

O

[Crasher]

It will probaly be dirty sensor prongs, in my work it is more economical to replace the tank, which has been revised from 4G0 121 403 AC to 4G0 121 403 AG due to... false low level readings; seek and ye shall find! They are £33.50 genuine retail inc. VAT or you can get one from fleaBay for £43! Autod0c stock the Mahle CRT 60 000S but I am always nervous buying from them.

[OmegaV6]

Many thanks for that, local indie has quoted me £90.00 to replace with genuine .... £30.00 for the part, 1/2 hours labour, antifreeze. Seems reasonable enough to me as I'd need to buy both the part and some antifreeze, and now I've turned 70 I don't fancy working on the car in the weather forecast for next week ! (no garage available, all work is done outside!!) ... booked in for monday morning

[OmegaV6]

Car went in yesterday for the work .. couldn't be done as the part failed to be delivered !!

So done today .. part #4G0121403AG - £27.92 , labour £45.00 .. dreaded VAT £14.58 .. total £87.50 .. no mention of antifreeze on the invoice, but some has been spilt around the tank !

Will have to wait and see if it's fixed the problem as won't be going far for a few days - nowt to with covid .. wife has a knackered knee and can't walk, so playing nursemaid !! - and I won't use the audi for short journeys.

[OmegaV6]

Ah well .. drove it for the first time today.... warning came up twice in 60 miles .. out after less than a minute both times, and was on a level bit of road at the time. Level checked .. spot on the "max" mark when cold. Got to go out again tonight so wil see how it goes before taking it back to the garage ......doubt I'll get much support from them however .....