My 2010 Seat Exeo, gasoline engine, with 50704 km is having a coolant issue. The level keeps dropping, triggering the check engine light, and the error memory says possible defective cable or plug connection. Could this be a simple fix, or a failing water pump? I've checked the fluid and don't see any leaks, but the level keeps going down. Could air pockets be the cause?

Seat Exeo Coolant Loss Issue

Low coolant and a check engine light? Rings a bell! I had something similar with my old Renault Megane. Have you looked at the radiator hoses for coolant leak signs? What about the water pump, any coolant around it?

Interesting. You mentioned checking the radiator hoses and water pump. Besides looking, is there a good way to find a small coolant leak, or tell if air pockets are forming?

I'd suggest a local repair shop. They can pressure test the cooling system for leaks. My coolant leak was so slow it was hard to see. It could be a loose hose or sensor, but better to check it than risk overheating.

Just a heads-up, the problem's solved. You nailed it. The workshop found a bad coolant temperature sensor. Replaced it, cleared the code, and the coolant level is steady now. Cost 95€, parts and labor. Thanks for the assist!