if there is a leak at the back near the turbo. Look at the coolant lines going in and out of the turbo and also look at the coolant line going into the Throttle body.

Not a difficult fix though. took me 15mins to replace my turbo coolant lines and another 30mins to block all the lines going in/out of my throttle body and IACV. Just remember to replace the stock clamps with new ones.

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RS Liberty - Because WRX's are only good for parts...