Check engine Light

appearing. It comes up with no other indications,

come on again for anywhere between 400 - 1000 miles or

wouldn't know anything was / is going to go wrong.

When was it last *dealer* serviced ?

Graham

Other than what Graham mentioned, have you had it tested for emissions? I believe that sometimes, at least here, the cars have check engine lights that go off because of emmission issues, which can change, and then the lights go off, and back on again when the emissions aren't right.

You might want to check that, but usually, you can pay a mechanic or someone with a reader to pull the codes out of the car and find out exactly what is troublesome.

It could be an O2 sensor or whatever. The Saab diagnostics tool should be able to tell. It might save you the cost of a new cat even.

Graham

Oh it was around 1998, I don't remember exactly...

Cheers, I hadn't thought of the emissions.

Whoa, people, come back down to earth here.

1. A check engine light ONLY lights when there is a problem related to emission controls not operating correctly or detecting a failure
2. The ONLY way to determine what the problem is is to have someone read the code out. It does not have to be the stealer or even an independent with a Tech II - an ODB II reader will do it (I don't know if UK cars meet some other standard... but all you need is a code reader).
3. The most popular reason for a check engine light is a loose gas cap. It causes a loss of pressure in the fuel system. I'd suspect that first.

But how? I would think the opposite; the fuel tank needs a small hole in the cap for equalising the pressure above the fuel.

The system will be slightly pressurised, with a relief valve in case of too high a pressure.

As others have said, you need to get the fault codes read. And this can be either via a Saab Tech2, a buddy with an OBD-II fault code reader or most garages inbetween. Be aware that just knowing what the fault code says isn't always enough - the information needs to be interpreted. Sometimes it may say that a given sensor is faulty, but the solution could be a replaced vacuum hose (rather more applicable to petrol models!)...

Cheers for all the info guys, at least I know where I need to look now, thanks, kds:-)

Ah, a diesel...

No no, petrol versions have a lightly pressurised fuel tank system...