Temperature gauge going into red

cute geoge

The temperature gauge in my octavia continually goes up on journey of 10 miles or less,once i flick on heater it drops immediately .The coolant level is constant and got termostat changed but no luck there but wondering could it be faulty reading before i try anything else .How would i check the temperature ,is it just a case of sticking a simple termometer into coolant once it gets hot and what exactly what should termometer read if the hand is gone into red

BlakeS94

Get a cheap obd2 scanner and check ECT temp that the sensor is reporting

John.G

All VAG cars for many years now will read the true temperature (assuming sensor ok) up to 75C, it will then read exactly 90C between 75C and 105C and then display the true temperature again if greater than 105C, if the temp is actually greater than 100/105C then you should see the water bubbling in the expansion tank, you can check it with a thermometer but be careful removing the expansion tank cap. A test VCDS or OBD reader may not show a true reading either as the temp sensors no longer have two channels. The radiator fan should gave come on if no fault with it or the sensor.

Depending on year built, the water pump has a electrically controller sleeve to vary its flow rate, these are fairly well known I think for giving trouble as well.

teediddlyeye

If it's an EA288 engine (after 2014 IIRC) checking anything other than the water pump is a waste of time and money.

cml387

DO NOT OPEN THE COOLANT TANK WITH A HOT ENGINE.

You'll get covered in boiling hot steam and be scalded badly.