First off, don't buy this car unless you have money to waste.If you get an emmisions warning light it will lead to this, and below are ways to fix the problem before it worsens. There are multiple problems that lead to the engine of a 2000 VW passat blowing. Lets start from the begining, First your oil cooler goes bad no indicator lights will come on, This goes on for awhile as you drive causing your oil's viscosity to go bad,I.E. oil cannot hold hot tempature's thus making you get a indicator light showing you have low oil pressure. In fact your oil has thinned out making the oil flow faster not cooling the engine enough. the engine and ecm compensate making your emissions burn hotter as it travels through the exhuast. the hotter burning emmsions makes you oxygen sensors and catalytic converter go bad along with the mass air flow sensor which makes the car idle roughly. The rough idle then leads to extra strain on the timing belt causing it to break. Now the fun part, when the timing belt breaks because of bad desgin it will also bend all of your valves in turn blowing the engine, in some cases this will also blow the turbo at the same time.

To fix the engine I had it rebulit, a new or used engine puts you well over $5,000.00 I had mine rebulit for $1,800.00 plus taxes making my grand total $2,200.00. You can fix the rough idle as a temporary fix by replacing the mass air flow sensor it will last for about 3 months, to properly have this problem fixed you must have the engine rebulit fixing your valves and timing belt, then you must replace your oil cooler along with manifold back on exuhast to muffler this includes mainfold, piping, both oxygen sensors, catalytic converter, muffler, and mass air flow sensor. Fxiing all that I have listed will make all indicator lights go away and be fixed I.E. Check Engine light and Emssions warning lights. I had my car fixed at Norm's Towing in Mt. Gilead Ohio 43338