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It sounds very much like there’s a blow-by problem with this engine. The pressure created by the combustion process is somehow getting past the pistons and into the crankcase, causing the dipstick to leave its tube and blowing oil all around the engine bay.

Blow-by is often caused by worn or broken piston rings or a damaged piston itself. But modern turbo-diesels are also prone to problems with their crankcase ventilation and emissions-control systems which can become full of gunk and not allow the crankcase to breathe properly. At which point, the same symptoms can occur.

A mechanic will be able to do some tests and determine what’s causing the pressure build-up inside the crankcase. If it’s internal wear, a rebuild may be required. But if it’s a build-up of crud inside the emissions-control systems, a manual disassembly and clean might be required. Either way, your car’s warranty might cover you for this, so the Hyundai dealer is your first port of call.

I can understand why the crank angle sensor was the first thing to be changed. These often start to die and the first symptom is an engine that stops after running for a while. But you’re right to be sceptical about the timing chain as there’s a theory that says if the engine runs properly at all, then the issue won’t be anything fundamental. Which is to say, if the timing chain was stretched beyond the point at which the engine could function properly, it wouldn’t function properly at all, regardless of how long it had been running.

A good workshop should be able to scan the car’s computer. If the timing chain really is stretched, then the computer should have logged this as a problem. If not, then you’re looking for something else. Of course, what that something else is the million-dollar question. Don’t rule out basic things like a dirty fuel filter which can allow fuel to flow for a while before the rubbish in it clogs the flow after a few minutes running.

That said, if the engine can’t locate the correct signal from the camshaft (which is controlled by the timing chain) it will sometimes look for a stand-in signal somewhere else on the engine, allowing it to start but not run properly. An electronic scan is definitely the way forward.

When a bunch of electrical functions all go out at once (or within a short space of time of each other) suspicions are always drawn to the car’s body computer. This computer controls all the functions you mentioned as well as dozens of others from the heating and cooling, central locking, lights, wipers, dashboard and much, much more. When the computer starts to die (as most computers eventually do) these functions will start dropping one by one and sometimes in simultaneous batches of failures. Eventually, pretty much nothing will work and the car will not even respond to the key’s inputs.

An auto electrician is the best place to take the car, and as well as the computer, they will also check the car’s battery and charging system and the quality (or otherwise) of the car’s earthing points. Bad earths can cause similar problems to this, but the body computer remains a likely culprit.