Dear EJO,

May this find you well. On a 940 series car, the On-Board Diagnostic (OBD) Codes can be "read" by doing the following:
(a) In the engine bay, on the driver's side strut tower (USA/Canada models), on the front side of the tower, you will see two rectangular black plastic boxes, 2" long by 1" wide.
(b) Start with the box closest to the engine. Grip the top of the box and lift. It should come off, but still be tethered to the base. You will see six openings. Not all of them are used.
(c) Going into the side of the cover, you should see a wire. Pull it gently from the top. You'll see it has a metal tip
(d) Put the metal tip into one of the six ports. If the tip fits loosely, that port is not used. When you feel the tip fit snugly, you have found a port in use.
(e) Press the round button and hold it down for three seconds. Release it. Watch closely. If the red light blinks - s l o w l y - 1 - 1 - 1. Then all's well.
(f) Go to the next port, that is used. If you get anything other than 1 - 1 - 1, write down the code, for example 1 - 2 - 3 . Make a note of the port designator (e.g., A2 = fuel system).

Once you have all the codes, go to the FAQs under SITE FEATURES. That should give you some indication of the problem. If you have a code not listed there, post back. I have a complete list of codes, in the Volvo pocket data booklet - Cars.

Do not disconnect the battery, until you have identified the problem and fixed it. Then, if the code persists, a battery disconnect may be in order.

Hope this helps.

Yours faithfully,

spook