Engine teperature sensor problem

[dovells]

Hi,
Had an intermittent problem with the glow plug light coming on while driving on our 1.6 turbo diesel.
Noticed the previous owner had disconnected one of the thermistors at the back of the main engine block and wired it up to a little resistor instead. One of the terminals had broken off so presumably caused the glow plug light to light as the wires bounced about.
Anyway bought a new sensor / thermistor from GSF plugged it in and all was sorted. Except that now when I try to start the engine when it is hot it really does take ages and ages to fire. Could they have given me the wrong sensor? Or could the previous owner have found a more complex problem and bodged it with a cheap resistor?
So does anyone know how to check the sensor or is there any other problem. Or could I just put in another resistor? If so what value as I threw the old one.

I dont really like electrics, which is why I like these vans.
Hope somebody can help.

Jonathan