Golf Mk4 Coolant Warning - Peter D
Golf Mk4 Cooant warning message appeared this morning but coolant level perfectly OK. The sensor appears to be two stainless rods immersed it the coolant header tank. Does this just measure that there is or is not coolant or is it really smart and measures the resistance across the pins to establish the presence of the correct proportion of anti freeze. The message has not returned and all is well. Regards Peter
Golf Mk4 Coolant Warning - Peter D
What No Response Regards Peter
Golf Mk4 Coolant Warning - Pugugly {P}
Have you checked the coolant's quality - keep an eye on the level, could be a computer glitch.
Golf Mk4 Coolant Warning - jc2
Sensor is for LEVEL not QUALITY.
Golf Mk4 Coolant Warning - Dynamic Dave
But if the sensor works on resistance and the quality of the coolant is poor, then this could well affect the resistance across the terminals.
Golf Mk4 Coolant Warning - Peter D
The coolant is clean and the prescribe red colour. The vehicle has a full VWSH with 80K on the clock. Regards Peter
Golf Mk4 Coolant Warning - Hamsafar
Check you don't have coolant migration into the sensor wiring. This was common around the turn of the millenia. The coolant leaks from the reservoir into the connector and 'wicks' down the wires and can come out the other end believe it or not! For further info. search www.google.com (not co.uk) for "vw coolant migration".
Golf Mk4 Coolant Warning - Peter D
It appears that the sensor ( two stainless pins ) actaully measures the restance thus the quanity of G12 in the water. By draining the heater and adding 1 litre of G12 the problem hase gone. Regards Peter
Golf Mk4 Coolant Warning - bigshineybike

A little off topic but.

Take care with coolant where G12 is invloved. It is worth paying the extra for genuine VW stuff.

Most car accesory shops or even mechanics will tell you that other types are compatible.

(look it up on google if in doubt and you have a few hours to spare.)

Our 2003 VW is F****d because a "mechanic" belived this.

when mixed G12 seams to coagulate into a sort of polymer which will block thermostats, heatewr core , radiator cores. on our car even the plastic components of the pipe work are springing leaks.