matthiasmeyer1

Coolant Vanishing Act CLA Trouble

My 2014 Mercedes CLA with the gasoline engine is playing games with its coolant. I have 147801 km on the clock. The check engine light is on, signaling low coolant. I've checked around the coolant reservoir and the cooling fan, but see nothing obvious. Could a defective cable or plug connection cause this, or is it a head gasket issue? I'm not seeing milky oil. The shop quoted 95€ for a diagnostic. The radiator cap seems fine. What could it be?

4 comment(s)

Coolant issues are a pain. I had a similar problem with my old Volvo V70. I was losing coolant with no visible leaks and the check engine light was on. Did you pressure test the cooling system? It could be a hairline crack somewhere that only opens up under pressure. Is your cooling fan running normally?

Pressure test? I haven't done that yet. The cooling fan seems to work, but I'll keep an eye on it. A hairline crack? Where should I be looking? Is that common?

The hairline crack on the Volvo was hard to find. It was on one of the hoses, buried down low. Since the Mercedes is flagging a potential electrical issue, it might be worth checking those connections before tearing into the cooling system. Otherwise, I'd take it to the shop for a proper pressure test. It'll save you trouble.

I took it to the shop. It WAS a faulty coolant level sensor connector. Corrosion had gotten in there. They cleaned it, replaced the connector, and the code is gone. You were right! Diagnostic and repair cost 95€.

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