Audi Repair: audi a4 1.8tsport 1997model oil temp gauge, temperature guage, mix ups

Question
the oil temperature guage on my audia4 as started playing up one minute its fine next minute its in the higher range of the gauge sometimes goes back to normal and somtimes stays in higher range i use synthetic oil and ive checked oil level which is ok

Answer
hi there!! sounds like a faulty Oil temp switch, though before replacing it  i would carry out preliminary checks to confirm no other problems exist.
the temperature switch is a resistor with a negative co-efficient which basically means as the temperature rises the resistance across it reduces allowing more voltage to pass through there by raising the needle on the guage, factors like loose or dirty contacts on the switch can cause false resistance there by creating false readings.

Also confirm the Gauge is working fine, this is done by removing the wire from the switch and connecting it directly to ground and watching the needle which should rise to the maximum level. if it sticks half way or doesn't rise at all then either your gauge is faulty or you have a problem in the circuit.

After the checks have been carried out and any faults rectified and the fault is still present I would then suspect the switch it self( which should be mounted on the block it self). its basically simple to replace  provided you follow a systematic procedure and make notes of what you removed so there is no mix ups when you return everything back.