Temperature Light Flashing

[farny1206]

hi there i have a 2001 galaxy tdi the temperature light has being flashing for about 3 months so i have been checking the water level every couple of days and the level has always been fine and the temp guage is running at 90 but we went on holiday last week and when on the motorway the guage went onto the red so i pulled over and took off the water cap and it spurted water and steam everywhere and the temp dropped back down to 90 at this time the fan was running so i know thats working fine. i filled the car back up with water and it ran fine after this it didnt use any water at all then on the way home after traveling for about 3 hours it did the same again but since we have been back traveling localy its running fine but the light is still flashing would a faulty temperature sensor or faulty thermostat cause this problem any help will be great thanks.

[seatkid]

Never remove the expansion cap while the engine is hot. To do so is to risk serious injury to yourself and damage to the cylinder head (local boiling) as well as lose coolant. Always replenish coolant with the correct level of G12++ antifreeze (40%).

 

The temperature sensor is a dual device IIRC, possibly its duff. Check the connection to the sensor as well.

[credless]

Had the same issue on my 2001 tdi - intermittent flashing temp warning light , turned out to be loose connector plug on the  expansion tank coolant low level sensor. Reseated and fine since. Don't think the temperature sensor is the issue as when this goes it usually causes idle speed to fluctuate as it screws up the ecu fuel air mixture commands .

 

The overheating issue maybe just a coincidence - head gasket failure pending!!

[farny1206]

thanks for your advice i will check everything you have advised later this week and will update everyone. 

Just one more thing i remembered is that up until it overheated the temp guage didnt work somethimes and in winter the heater sometimes blew cold just wondering if this has anything to do with it.

[chrispb123456]

Certainly sounding like head gasket failure, but do check the water pump impeller first, do this by removing thermostat housing from block and feeling the impeller is secure on the shaft, and test stat while removed

 

 

Also check auxiliary water pump (run on pump) as this also aids circulation (on bulkhead behind fuel filter)

 

iirc flashing temp light when gauge reads normal is wiring fault at the bottle sensor.

Edited July 16, 2013 by chrispb123456