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Intermittent indication of low coolant level


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Greetings, everyone.

Experiencing coolant warning indicators during cold starts, which began occurring this winter at low temperatures. Essentially, the issue occurs when starting the vehicle and disappears after the coolant has reached a warm temperature or when the temperature gauge is at least halfway up while driving.

Upon inspection, I saw that the coolant level is over the minimum need but below the maximum limit. There are no visible indications of any leaks below the vehicle. I already added coolant to get it to the maximum level last week, nevertheless the warning light continues to appear.

Do you have any suggestions or thoughts?

If I ultimately replace the coolant tank, are there any considerations to keep in mind while adding fresh coolant? For example, add coolant to the tank and pressurise it to ensure there are no air leaks in the system.

Thank you.

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I would assess the resistance of the fill level sensor on the tank and juxtapose it with that of a verified operational sensor. It may be apparent that the sensor need replacement (uncertain whether it can be detached from the coolant reservoir?). If you are considering replacing it, I think Audi has introduced a strengthening strap as a retrofit measure to prevent the tanks from separating. I am currently unable to locate any information on the subject, but I am certain that it had significant importance. I would likely include it for the sake of durability.

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I have recently examined the engine bay trim and removed it to access the coolant. I am unable to detect any indications of leakage or any regions that are damp or marked with moisture. The appearance suggests extreme aridity.  Last week, I completely filled the fuel tank to its maximum capacity. However, after doing so, the warning light indicating low fuel still appeared. In an attempt to resolve this issue, I drove the vehicle for a drive, thinking that it would need a reset. Consequently, the warning sign disappeared. However, after a week, the warning sign has reappeared once again. I have a little suspicion that the coolant level is below the maximum mark after refilling it. However, it is still more than the minimum value. I am certain that I filled the coolant till it reached the maximum level. However, I am unsure whether it is necessary to wait for a few minutes for the liquid to settle and then refill it again. But is clearly below max again (but remaining above min)

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These enclosed systems often experience reduced performance in freezing temperatures during winter months, leading to low readings on the indicator until the systems reach their optimal working temperatures. Add about one cup of coolant, ensuring not to exceed the recommended amount.

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There was a Technical Service Bulletin (TSB) issued for the coolant tanks of the first generation. Over time, the tank might gradually develop cracks, necessitating the installation of a strap as a solution. It would be advisable to verify whether that has already been accomplished.

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Greetings, everyone. If the recall has been done for the strap around the tank, do you know whether they can be changed over to a new tank?

I will try to add extra coolant again at some time today and see.

 The user's text is a single letter "S". Curiously, this issue began occurring as the temperatures decreased in the UK, but it ceases whenever the vehicle reaches its optimal temperature.

Apart from the coolant tank (since I cant see any leaks or symptoms of leakage) is there anything else that might cause the coolant warning light to show up on the screen then go away after vehicle is up to temp? Could it be a water pump?

I plan to visit a buddy today in order to connect my vehicle to their VCDs/diagnostic equipment.

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Although I often support individuals doing a thorough examination, I believe it will not be very beneficial in this case. The possible causes for the issue are either the detection of false negatives or the identification of a "implausible signal", both of which indicate a malfunctioning level sensor circuit.

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