I have a 2013 1.6 Octavia and have been losing coolant for 3/4 months, intermittently, but more regularly on motorway runs. After having a pressure test done showing no leaks at my local vag specialist I went to Skoda main dealer. They think it’s the charge air cooler leaking internally and want just shy of £1500 to replace it. However, I’m not convinced they’re correct and done want to waste that amount of money. I’ve noticed that the coolant is coming out of the relief valve on the expansion tank, as it’s wet underneath and the uv light shows the coolant residue there. Could this still point to a charge air cooler fault? Thanks 

I suppose they could be right, if there is a leak in the charge cooler it would over pressurise the coolant system when under boost and could cause the expansion tank to blow coolant out and with normal driving you may be burning a small amount of coolant.

 

Your local VAG specialist may have only done a pressure test with the car cold or cooler than operating temp and the crack may not open up until its hot.

 

 

Charge air cooler replaced, failed! Still losing coolant. Back in the dealership next week.

44 minutes ago, sboothd said:

Charge air cooler replaced, failed! Still losing coolant. Back in the dealership next week.

 

£1500 refund then,

Sounds an absolute weird one. I have the same issues in March 2015 Skoda Octavia. 
is your heating working correctly? 

it’s possibly could be your heater matrix is blocked.  Next time the car generates the DPF check if you’re losing coolant from the expansion tank.  
have you looked at your EGR valve cooler