Strange coolant temp issue, suppose to be taking the family on holiday!

[franky]

I've a random problem on a 2003 1.9tdi 115bhp.

the engine temp(water) gauge seems to be all over the shop, not sitting at 90 like normal. It moves up and down from 60ish to 90 at will and at speed.

Spends most of its time at 70ish on the gauge.

Using VCDS lite it seems that the gauge doesn't match the temp shown. Even with the oil at 100deg C it will randomly drop. Oil temp is constantly stable once warm. It did have a fault of temp sensor showing but I cleared it and its not appeared in the past 150miles even though the above is happening.

A few times its caused a strange loss of power, say 3 times in the past 400miles.

Is this related? MAF values seem normal under load. The car starts easily and pulls smoothly.

Sticky thermostat maybe?


I'm suppose to be taking the family to France very shortly....

[martin1810]

I would check the coolant sensor wires and probably fit a new sensor. It is a dual output sensor. The car may run odd if the ecu looses the signal from the coolant sensor because it uses the signal for fuel control.

[Chipped2]

I had similar issues with my 2002 Passat TDi 130 Sport AVF giving erratic temp gauge readings although the car appeared to be running OK. Subsequently bought a VCDS which showed from memory a G62 sensor issue. Fitted a genuine VW replacement green one in place of the original black one which not only restored performance that I didn't realise I'd lost but has paid for itself...£30...many times over in increased mpg. If your sensor is black, replace it anyway.

Easy to replace after you have the experience of doing it once! Very little coolant loss too. Crasher kindly posted a picture of where the sensor was located as it is not that easy to find. You will need Sensor, o-ring and plastic retaining clip.