There are plenty of reasons why a diesel won’t start in the morning. This can often be traced back to a problem with the fuel system or the glow-plugs which are needed to warm the combustion chambers before the diesel will ignite.

As for the noise, it pays to remember that diesel engines are inherently noisy, but if you’ve owned the car for a while and are familiar with its normal level of racket, then any new or louder noises signal a problem. If, indeed, the new noises are connected to the engine’s refusal to start easily, you might be looking at an engine with worn out internals. At that point, it’s time to recondition or replace the original engine.

But before you do any of that, have a diesel specialist look at and listen to your engine running, and you might find the problem is a simple one after all.

It all depends on the model and variant of the vehicle you’re talking about, but, generally speaking, the fuel rail pressure sensor on a turbo-diesel engine will be somewhere along the fuel rail. But, even if you know for absolutely certain that this sensor is the problem, we have to advise against any amateur mechanic taking on this, or any other, job that deals with the fuel system. That’s because the fuel systems on a common-rail turbo-diesel run at incredibly high pressures. So they’re dangerous things to fiddle with.

In some cases, the pressure could be enough to slice fingers off. Which means you have to know the exact process to follow in order to bleed off any residual pressure in the fuel system (even if the engine hasn’t run for days) before you can safely tackle jobs like this one. Leave it to the experts, in other words. Also, a specialist is a chance to be able to make a more accurate diagnosis than the one given by an online forum of dubious credibility.

When a whole bunch of electrical and convenience items go on the blink all at once, the prime suspect is the vehicle’s body computer. This computer controls all the functions you’ve mentioned as well as plenty more including the entertainment and climate-control systems, the powered seats (if fitted) and even things like the seatbelt warning lights and buzzers.

An auto electrician is your best bet at this point, and chances are they’ll have seen this exact problem on similar models. Ultimately, you’ll probably need to replace the body computer, but you can try this trick first. Disconnect the car’s battery and leave it disconnected overnight. Next morning, hook it back up and see if the various functions have returned. Disconnecting the battery will sometimes force a reset to the factory settings and will return the body computer to normal service. It’s not a guarantee, but definitely worth a shot since it costs nothing to do.