Mercedes GLC Diesel bypass valve and overheating issue

I had a similar issue on my GLC. Check the entire vacuum system, especially the lines connected to the exhaust system. A leak there can cause a cascade of errors, including bypass valve issues and eventual engine overheating. Did you notice any power loss before the overheating

Power loss was indeed observed prior to the engine overheating. Is the vacuum system failure a common issue on this engine

Vacuum leaks are fairly common across Mercedes models, especially as they age. Given the power loss and the consequential bypass valve error leading to engine overheating, I'd strongly suspect a leak. A smoke test at a workshop is probably the best next step.

Vacuum leak confirmed. Consequential error as suspected. No cost incurred. Thank you for the insight.