Your glow plugs will only work if the temperature of the water in your cooling system is below a preset setting, this is controlled by the sender unit in the thermostat housing. On vectra c there is only one sender.
On vectra b there are two, big one for glow plugs, little one for temp gauge. It may be vauxhall need to plug in and reset the ecu, check the sender units first.
Pete Bevington, October 2009
