I recently had engine light coming on, acommonproblem wasthe fuel cap as there was a known problem with the earlier saab 93(52 plate) new shape.
Now replaced but it feels looser than original, and yes light back on.
I ordered it from saab, told them the model, but thinking back they never asked if it was petrol or diesel, are they the same??
If they are the same surly it should feel tight when put on(to make it gas tight)