Rav4 2018 diesel losing coolant

[Wasshigguk]

Twice in the last 3 months I've had an overheating problem with my Rav4 2018 2.0l diesel first time after having  the var a month overheats and I have to fill it with coolant 4ltrs all seems fine checked by dealer didn't have any problems  till two weeks ago noticed coolant low topped up then today lights flashing overheating  warning pull over had to put a further 2 ltrs in it but can't see where it's going anyone had this problem  

[Derek.w]

You may be loosing it through the exhaust as a head gasket or turbo issue.

Have the garage sort it out that you purchased it from under warranty.

You can try just removing the radiator cap and lets say run engine at 2000 rpm or less and just see if you see any air bubbles, after that overfill rad on purpose afterwards so excess is pushed into expansion bottle.

Press the hose to help air escape by hand.

Note set cabin temp to max before doing the all the  above.

[tfc]

You can buy a combustion leak tester fairly cheaply, you can buy them off eBay but I don't know how good they perform for around £5 - £30, I have one but it's  a snap on,  in the region of £100.