Which heat sensor or what is going on please ?

[mikemusic]

I think I have 2, possibly 3 separate problems - or is it one ?

Saab 9000  1996  2.3T

1. Anaolog water temp gauge is always on cold. Don’t think it ever moves

2. If stuck in traffic or stationary with the engine running the digital temp gauge goes up quickly, 10 -15 minutes temp goes over 20’c in the winter. Been 30'c in the summer in one jam.
I know this is to give outside temp but I'm sure it is picking up heat inside the engine compartment. Water is overheating as fan is not cutting in. I've lifted the bonnet after one f these episodes and it was *hot*.

3. When I turn the engine off the fan runs for a couple of minutes, even if I have only moved it out of the garage.

My mechanic thinks I need a sensor or two.

What thoughts here please ?

[sgould]

As long as a gauge is working, it can only read what the sensor tells it.

Then you have to work out whether the sensor is working.  If it is, then something else is broken, like the thermostat.

A permanently low gauge suggests a sensor or gauge failure.  A stuck open thermostat normally had the gauge showing normal in traffic and low on the open road.  If its stuck shut things will boil.

[phoenix]

There's two temperature senders on the 9000, one on the block for the engine ECU and another on the thermostat housing for the dash gauge and the fan control. Earlier models also had a thermoswitch on the radiator to control the fans, but on yours it will be governed by the ECU.

It sounds like it may be as simple as it has become disconnected. Have a look around the thermostat housing to see if there's a two pin plug/socket not attached to anything.

[mikemusic]

Thanks very much guys

I will have a look around at the weekend