What must you do if the oil pressure warning light fails to switch off after starting the engine?

You answered correctly. The oil pressure warning light indicates that the engine's oil pressure is too low, which can cause serious engine damage. According to German traffic rules, if this light does not go off after starting the engine, you must first shut down the engine immediately to prevent damage. Then, you check the engine oil level to see if it is too low or if there might be a leak. Continuing to drive without addressing this warning is dangerous and not allowed, as it risks severe engine damage. This procedure helps protect the vehicle and ensure safety.