It can wait, but if you notice a drop in mpg to the teens, it might then be worth fixing or replacing it.

Now that you know what the code reader is, I suggest you spend a little time and go through all of the A and B slots. Attempt to erase all of the stored codes untill you get 1-1-1 everywhere except B-2. B-2 will return a 1-2-2, which is for the cruise control and must be ignored.

Your car is old enough to warrant checking vacuum lines in the engine compartment. Especially the vacuum elbows! They tend to crack, allowing air to get in and changing the engine dynamics. Look around the intake manifold first and then make your way to the radiator shroud. If it is suspect, wrap them with electrical tape as a stop gap measure, two or 3 coats, until you find that you can affort to order some new elbows.

Go to Sears and buy a folding Torx tool for $5. 6 different Torx drivers to fit most of the screws in the 850. You will find you cannot live without it, and it stows in the glove box or armrest.

Klaus
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I still miss my 164 and my 854T. Just driving a V70R :)