2005 SAAB 9-5 Arc Wagon

[mnikzad1]

Does it have Timing belt or chain and how often do I have to change the water pump?

[Finding41]

2.3L= Chain.
When it leaks or the pulley gets close to or starts to wear into the timing chain cover. Check it when You do the timing chain.

[Burnsside42]

When the water pump leaks = replace. Some last 20K Some last 200K It's a part - it will fail eventually.
Timing chain you almost never have to replace - but if you ever do, it's best to replace the guides, tensioner and anything else along the way.