The 900 engine is reliable and capable of extremely high mileages as long as the oil and filter have been changed when necessary.
The oil in the turbo needs to have been changed as per the service schedule at least. A full service history is pretty much essential; it is especially good if it is a SAAB one.
Check for any blue smoke when starting the engine. This can be indicative of a turbo needing replacing.
Start it up and take it to about 3000rpm, it should sound smooth with no harshness or rattles - rattles can mean that the timing chain needs replacing.
Check for oil leaking from the head gasket or rocker (valve) cover gasket.
A high pitched whining or whirring sound from the engine, that rises and falls with the revs, can be indicative of the idler pulley, tensioner pulley and serpentine belt, needing replacing but this is not a huge job and the parts are not that expensive.
The Direct Ignition module in the turbo model can fail leading to difficulty starting and the engine just 'dying' it is easily replaced but rather expensive.
Transmission
Check the operation of the gear change, there were problems with the gear linkage on the early models (mainly 1994 & 1995) and this usually manifests itself as difficulty in selecting reverse and/or second and will require a replacement linkage to correct.
Check that you cannot put the car from reverse into neutral when the key is out of the ignition.
The cable operated clutch can be very heavy to operate especially when the clutch is worn but can be rectified by replacing the clutch and cable.
Avoid the Sensonic, unless you really want one, as it is expensive to repair if it goes wrong.
Check around the gear selector shaft seal as it is prone to leak on manual transmissions.
Check for oil leaks from the drive shaft seals
Suspension and Steering
Listen for a knocking or 'clunk' sound from the front suspension when going over bumps (such as speed ramps), during braking and/or on initial acceleration. This often means that the upper suspension mounts need replacing. This is not a difficult job for the serious DIY'er to undertake.
Listen for a load clicking noise from the drive shafts (meaning that they are failing) whilst driving slowly in a circle at full lock. Check this in both directions
Check the steering rack for signs of leaks from the gaiters.
Check for a 'banging' noise when steering. Especially if going from one lock to another. Due to the steering rack being fixed the bulkhead (firewall) and flexing it can lead to cracking of the bulkhead by the mounting points. This is about £700 to get fixed.
Check that there is no play in the steering (push and pull the steering wheel)
Take the vehicle for a drive and check that it holds a straight line without pulling to one side or 'crabbing'. If it does it may be correctable by getting the tracking done but it has been known for owners to use the rear axle as a jacking point. This can deform the axle and will usually require replacement. Very expensive!
Brakes
Check the discs (rotors), especially the rear ones, for corrosion on the face. This indicates a possible seized caliper or that one of the brakes pads has seized. This will require a strip down of the brakes to resolve but the parts are not expensive and the work fairly straight forward.
Check action of handbrake as these can be difficult to keep adjusted correctly and even when they are correctly adjusted they need to be pulled up all the way to engage properly.
Body
Check out the bottom of the doors, the top rear shock mounts, the outer edges of the rear wheel arches, and the jacking points for signs of rust. Surface rust is treatable, but if it has taken a firm hold on load-bearing parts walk away.
Check that all the washer jets work, that the headlamp wipers work and that they 'park' correctly after use
Interior
Make sure that the A/C or climate control works correctly and also check for any sign of damp in the passenger side footwell. This can be a sign of problems with the A/C, but it is usually as simple as a blocked drain hose which is easily cured (and could be used as a method of getting a price reduction)
Check the upholstery. On the earlier models the stitching on the seats could start to come undone.
If fitted, make sure that the heated seats are in full working order.
Check that all the pixels in the SID (the display unit above the radio) are working.
Make sure the dashboard illuminates and that the dimmer for it works. The rheostats are known to fail.
Press all the knobs and make sure that everything works and lights up.
Audio
Check the stereo particularly the AM reception.
Make sure that the seller has the security code for the radio. Although you can get this information from SAAB if need be.
