Firstly we need to know what engine you have, they don't make a 1.9 tdi - well not in a Peugeot anyway. It will either be a 1.9 XUD or a 2.0 litre Hdi which would be from '99 onwards, they are very different engines and need different diagnosis.

Right, that helps, although 'S' sounds early for an Hdi. Does the engine actually fire when you try to start it and the stop, do you get any smoke from the exhaust while its turning over?

The solonoid mentioned is on the earlier cars with the 1.9 engine, the most likely problem with an Hdi is the fuel pump fitted in the fuel tank, you should be able to hear ir run for a couple of seconds when you turn the ignition on.

That's quite correct if its a 1.9 engine, as far as I know the Hdi doesn't have one but if its smoking that indicates that fuel is getting in, failure of the solonoid will prevent this. Did this suddenly happen or have there been previous problems? This sounds to me like a 1.9 engine, does it have a fuel pump with a pipe going to each injector?. If that has happened suddenly I would suggest that the cam belt has slipped a tooth or two and put the timing out.