Punto Coolant Loss

I had a similar head-scratcher with my old Renault Megane a while back. Coolant disappearing act, no visible leaks, the whole shebang. I was convinced it was the head gasket too, but turns out it was a tiny pinhole leak in the radiator itself. It was so small, it'd evaporate before it hit the ground. Is your cooling fan running constantly by any chance? Could be a sign of engine overheating from the low coolant.

Thanks for the quick reply! The cooling fan does seem to be running more than usual, now that you mention it. Where exactly was the pinhole leak on your Megane's radiator? Was it easy to spot once you knew where to look?

It was a proper pain to find! It was on the engine side, near the bottom. Honestly, I only found it when the mechanic pressure tested the system. Before that, I was chasing ghosts. Given the fan running more, I'd seriously consider getting a pressure test done before you start any major work. Save yourself the headache. Might be a cheap fix, might be something bigger, but at least you'll know.

Cheers! I really appreciate the insight. I took your advice and got a pressure test done. Turns out there was a minuscule leak in one of the hoses, almost invisible to the naked eye. Replaced the hose, topped up the coolant, and the check engine light is gone. Repair cost me only 52€. I owe you a pint!