You could try all of the OBD ports and see if you get any fault codes. The A-1 is normally the transmission, the A-2 is engine, and A-3 should be the ABS. At least that is for the 940, same year. You insert the probe in one of the holes, and with the key in position II, press the little black button in the box for about 1 second - the red light will glow when you do this. The system then responds with a blink of the red light. Count the flashes, 1 through 9. There will be a slight pause between each number with each code being 3 numbers in total. A result of 1-1-1 indicates no codes present.



No, the OBD is not for dealer rip off. It helps them to narrow the search for the problem.

As for cleaning the sensor rings, yes, but do NOT use compressed air!! That is super fine particles and can lodge in the lungs. I would use a spray bottle and wash the sensor rings, or use a shop vac. It can get crusty.

Also check the sensors themselves, make sure they are pointing toward the ring and the wiring is not compromised.

An ABS malfunction will not have any affect on your breaking ability, it is only there to prevent brake lock up.
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Keeping it running is better than buying new