Mercedes GLK Coolant Level Issue

Low coolant in a Mercedes GLK can come from a few places. Checking the radiator cap is a good start. Check for less obvious coolant leaks, like the water pump weep hole or small cracks in a hose. Air pockets are possible, but usually happen after cooling system work. The error about a cable or plug connection should be checked. Make sure the sensor connections are secure and not corroded. Even if the cooling fan works, be sure the engine isn't overheating. I had a similar thing with my BMW 3 series. Before you go to a shop, have you checked the coolant level sensor?

Interesting. Thanks for the BMW comparison. Coolant level sensor, you say? Where is that and how do I check it? Can I see damage, or do I need a tool? If it was the sensor, would that cause the low coolant warning, even if the level is okay?

The coolant level sensor is usually on the coolant expansion tank, sometimes built into the tank. You might see a cracked sensor or corroded wires. A bad sensor can cause a low coolant warning even if the level is fine. Since the error codes point to electrical problems, it's possible. I think you should get it checked at a good shop. The repair should be around 95€. They can find the problem with the right tools. It sounds like you've found the problem and should have the wiring and connection checked.

Okay, thanks for the advice. I appreciate the help. I'll book it in. It was the plug connection to the coolant level sensor, and luckily the coolant loss was small. The bill was 95€, about what I expected.