temp gauge not working..

[madmax]

for a few weeks now ive had no temprature gauge working and this only started after my oil cooler went, replaced two sensors including the one that goes to the ecu no diffrence..so took it to dealer who plugged it in and said it was a faulty gauge which meant changing the complete set of clocks, as its a fixed unit...then couple of days ago decided to change the antifreeze run all the water out kept engine running to the last few drops, top up again, took it for a spin and it started to work but not as high as normal...then left overnight and not working now weird...any suggestions...!!!

[theolodian]

The one that goes to the ECU has nothing to do with the gauge.  It is a single-wire spade connector at the back near the oil cooler.  You will need to take off the scuttle, but then you can check the connection there.  May just be a matter of wiggling it.  Worth a try.

[TheBoy]

If they think its gauge, if its a 98 or later, they can prove with Tech2.

Whatever year it is, gently but firmly press back where tacho is (thats where connector sits behind) and see if connector wasn't fully seated...

Though the fact that oil cooler was changed, does point towards the sender (the on with brass top that the spade connector fits on...)

[Marks DTM Calib]

The dealer should have read the coolant temp with tech2 and compared it to the gauge....could be the stat stuck open...this would confirm it...

But, as a diy, check the sender conenction on the coolant bridge (its a single lucar connector)

[Matchless]

The wire can corrode inside the connector on the sensor, if it looks green cut it off and crimp on a new one.
Should be able to reach it with the scuttle off, touching the wire to ground will test the gauge.
One thought....if they used the wrong washers for the coolant bridge then the sensor will have lost its earth connection...but so would the ecu temp sensor....if its also using lots of fuel it might be worth checking this.