Coolant disappearing quickly in my 2018 SQ5 - overheating warnings!

ClearTheCode admin answer:

Coolant loss and overheating warnings on a 2018 Audi SQ5, especially with a sweet smell, often point to a failing water pump or a leak in the cooling system. This is a known issue on some V6 engines.

Here’s what you should do:

1. Check for Visible Leaks:
   • Carefully inspect the area around the water pump (typically on the front of the engine, near the accessory belt). Look for white or pink crusty residue, which indicates dried coolant.
   • Examine all coolant hoses, the radiator, and the expansion tank for cracks or drips.
2. Monitor Your Gauges:
   • Pay close attention to the engine temperature gauge. If it starts to climb rapidly, pull over safely and shut off the engine to prevent damage.
3. Check for OBD Codes:
   • Use an OBD-II scanner to check for diagnostic trouble codes. A common code associated with cooling system issues is P2181 (Cooling System Performance).

Common Causes:

• Water Pump Failure: The plastic components of the original water pumps can degrade over time, leading to leaks. This is the most frequent culprit.
• Thermostat Housing Leak: Similar to the water pump, the thermostat housing can develop cracks.
• Hose Leaks: Degraded or loose coolant hoses can also be a source of leaks.

When to See a Shop:

• Immediately: If you continue to get 'Engine Temperature Too High' warnings, or if the coolant level drops significantly after a short drive. Driving with an overheating engine can cause severe and expensive damage (e.g., head gasket failure).
• As soon as possible: Even if the car isn't actively overheating, persistent coolant loss needs professional diagnosis and repair. A qualified Audi technician can perform a pressure test on the cooling system to pinpoint the exact source of the leak and recommend the appropriate repair, which often involves replacing the water pump and thermostat assembly.