This engine has a reputation for failed EGR valves which are part of the emissions control system and live within the rocker cover. Without this valve working properly, the car’s tailpipe emissions can be higher than they should be, as well as causing the oil leak you’ve noted. And any time you have oil hitting a hot exhaust system, there’s the potential for a fire.

In some cases you can simply change the EGR valve, but experience suggests that with some engines, the solution is to replace the entire rocker cover which will incorporate a new EGR valve. The parts can usually be bought online.

Unless the water has come up through the floor and somehow got into the seatbelt mechanism or parts of it, the most logical answer is that rainwater has entered through an open window, run down the seatbelt webbing and into the mechanism under the seat. Failing that, if the floor and carpet has somehow got wet in the past, some water may have leached into the mechanism.

The question is: how do you know this has happened? The pretensioners only ever fire in the case of a collision, so their condition is pretty much an unknown until you need them. If, however, you’re referring to the inertia-reel mechanism that locks the seatbelt when you pull on it suddenly, then I’m sticking with the open-window-rainstorm theory, as water could definitely run down the belt webbing and into this part of the seatbelt assembly. Failing that, the moisture could be condensation that collected if the vehicle had been stored in a damp environment for some time.

Going back to first principles, anywhere that a power wire that should be insulated is allowed to touch an earthed part of the car is a potential source of a short circuit. As such, there are about a million places where a wire or cable carrying 12 volts from the battery could be shorting out by touching an earthed part of the car.

Typical sites of a short-circuit include anywhere where a wire runs through a metal bulkhead (say, from the car’s interior to its engine bay) anywhere a wire is continually flexing (the wiring inside a door jamb where it passes through the body) a switch of any sort or anywhere else where friction could have worn away the wire’s insulation. Sometimes the insulation just gets old and falls off the wire (Mercedes-Benz cars from the mid-90s were notorious for this).

The clue will be in what components have suddenly stopped working. Checking the fuse box to see what fuses have blown in response to the short circuit is also a good indicator or where to start looking. If you suspect the short-circuit is at the battery itself, there will be no need for forensic investigation; a short at the battery will produce a violent spark and lots of smoke. Unless, of course, the car is fitted with a great safety feature called a circuit breaker on or near the positive battery terminal. If you’ve suddenly lost all power to the car, that’s where to start looking.

Finally, don’t assume that a loss of power to the car or some of its components is due to a short circuit. Sometimes a fuse can simply fail for no good reason and call a halt to play. If you’re unsure, an auto electrician can work miracles that the rest of us cannot generally fully comprehend.