Audi Q5 Coolant Loss Mystery: Hidden HG Failure Alert

As someone with some experience working on cars, I had a very similar issue with my 2014 Audi Q3 2.0T last year. Initially thought it was a coolant leak too, but after proper diagnosis, it turned out to be a faulty connection to the coolant level sensor. The symptoms were identical, check engine light, low coolant warnings, and constantly having to refill the radiator fluid. No visible leaks under the car had me worried about internal issues with the water pump or worse problems. Took it to my regular workshop where they performed a pressure test on the cooling system. This ruled out any major issues like a blown head gasket. They discovered the wiring connection to the coolant level sensor was corroded, causing false readings and system warnings. Total repair cost was 95 Euro including parts and labor. To better assist with your Q5 issue, could you share: Are you noticing any white exhaust smoke? Does the engine temperature gauge stay normal? Can you smell any sweet coolant odor while driving? Have you noticed any air pockets in the coolant reservoir? These details would help determine if your issue matches what I experienced or if you might be dealing with something different in the cooling system.

Thanks for checking my case. Car details: 2016 Q5 2.0T, last service at 60817 KM. After reading your experience, I checked the exhaust, no white smoke at all. Engine temp stays completely normal, and I noticed a faint sweet smell near the engine bay. The coolant reservoir shows small air pockets when I check it cold in the morning. Had the shop do a pressure test yesterday. They found hairline cracks in the radiator hoses near the clamps. Also spotted a very slow drip from the water pump housing. Explains why there was no obvious puddle, it was evaporating before hitting the ground. Might be worth checking the hoses and pump seals on your Q3 too, since they tend to develop similar issues around this mileage.

Thanks for the update on your Q5. The symptoms definitely point toward a different issue than what I had with my Q3. While my sensor connection was the culprit, those hairline cracks in your radiator hoses and the water pump leak create a more complex cooling system problem. After reading about your pressure test results, I had my Q3 checked as a precaution. Everything looks good for now, but the mechanic mentioned these cooling system components often start failing between 60000-80000 KM. The engine overheating risk isnt worth ignoring even small leaks. My cooling fan sometimes runs longer than usual lately, so Im keeping an eye on the coolant level. Your case reminds me to stay proactive about maintenance, especially with these common wear points. For your Q5, replacing both the hoses and water pump at once makes sense since theyre already showing wear. This should resolve the coolant leak completely and prevent any engine overheating issues down the line. The sweet smell you noticed is typical of a coolant leak, but should disappear once the repairs are done.

Thank you for the helpful insights. After getting the pressure test results, I decided to have both the water pump and radiator hoses replaced. Total repair estimate is 850 Euro, which seems reasonable considering the parts and labor involved. The mechanic showed me how the old water pump housing had developed minor corrosion around the seals, causing that slow coolant leak. The original radiator hoses were also showing their age with those hairline cracks, especially near the clamp points. This explains why the coolant reservoir needed constant refills despite no obvious puddles under the car. Good thing I caught this before it led to any major engine overheating issues. Will update the service records to track when these cooling system components might need attention again. Appreciate the suggestion about preventive maintenance. Planning to have the coolant system pressure tested annually now, especially since these Q5 models seem prone to developing similar issues around this mileage. Better to catch small problems before they become expensive repairs.