Turbocharger failures can often be identified by noting that Small puffs of grey/white smoke begin to stream from the tailpipe when coming to a stop. This is usually an indication that the clearance between the impeller shaft and bearings have become excessive allowing oil to leak past the seals. Another indication of excessive bearing clearance is noting that large amounts of oil show up in the intake manifold.
NOTE: In most cases you can pull the hose that goes to the compressor side (silver aluminum side) and see if the veins on the turbo shaft can be moved manually. If not, the turbo is seized and must be replaced. Keep in mind that some failing turbochargers will only lockup once the engine is running because the veins will jam against the side of the compressor housing once the turbo spools up.
Thanks to Abdul Aziz for contributing to this FAQ!
I think the course of SAAB 95 Turbocharger failures is clogged catalytic converter. After replacing 2 Turbochargers in my SAAb 95 2000 model, I removed the catalytic converter and cut it apart to find it is almost completely clogged.What is happening is when you speed up with care the preesure builds up in that portion and week point is turbo seals which it fails & you have to replace your turbo. To save SAAB turbo insure the catalytic converter is not blocked.
NOTE: Clogged converters can cause excessive pressure at the turbo. Whether or not this causes the turbo's to fail is questionable but we do know that it is not good for the turbo's at all so checking the converters for blockage is a good idea regardless.