GLC Hybrid Coolant Vanishing Act

I also drive a GLC. I had a similar issue last year. It started with the low coolant warning light popping up sometimes. I topped it off a couple of times, but it kept happening. Have you checked for any visible coolant leak around the radiator hoses or the water pump? Is your cooling fan running a lot?

Thanks for the quick reply. I did a quick visual inspection but didn't spot anything obvious. I'll take a closer look at the radiator hoses and water pump area specifically. The cooling fan does seem to be running more than usual, especially after shorter trips. Could air pockets be the problem, or am I being too optimistic?

Air pockets are possible, but unlikely to cause such a persistent issue. With the fan running more and the level dropping, I'd bet on a small coolant leak somewhere. Mine turned out to be a hairline crack in the expansion tank, hard to spot until it got worse. I'd suggest getting a pressure test done at a workshop to pinpoint the source. It's better to find it sooner rather than later.

I appreciate the advice. I suspected it was more than just air. I dropped it off at the shop this morning. It turns out it was a faulty connector on the coolant sensor throwing a code and causing the low coolant warning. A new connector and a top-up, and I'm good to go for 95€ Thanks again for pointing me in the right direction.