Temperature trouble
This 1998 Volvo 940 was running perfectly and the owner had only one complaint, which was that the temperature gauge was continually on cold. His main concern was that he would have no warning if the engine began to overheat.
There are two temperature sensors on the cylinderhead: one for the temperature gauge and the other for the engine control unit. The sensors are not expensive and he decided that if one had failed the other might do so soon. Two new sensors were ordered up and, as it was time for the coolant in the Volvo to be changed, the radiator was drained. Normally the sensors can be replaced without a great loss of coolant, but combining the two jobs on this vehicle made sense.
Sitting just under the inlet manifold the sensors are not easily accessible, but with care can be quickly replaced without too much fuss. Once in place, the cooling system was refilled and bled out. The engine was then run up to temperature to confirm all was now in working order.