In 1992 I had intermittent speedometer/odometer issues with my Alfa Romeo Spider. The trip odo would continue counting while the car was at a complete stop! I brought the car in any number of times but the techs were never able to reproduce the problem until ONE YEAR LATER. During that time, along with many heated arguments with service staff, I had several conversations with Alfa's USA HQ in FL, and they finally sent a field technician up to oversee the work on the car. He was the one who called with the news to say they had seen the speedo jump and the odo move (after keeping the car for an entire week). Talk about relieved!

My point is this -- keep at it and get corporate HQ involved. My situation resulted in a TSB and rewiring of the starter (along with lots of apologies and freebies). If you refuse to drop your complaint, hopefully you eventually will find a cause and a solution!

 

I suggest you have them start by disconnecting and reconnecting all the wiring harness connections related to suspension. I sounds like a short or loose connector!! Can be a real bitch to find! If the probelm is still there after the "faulty" sensor change, might I suggest that that section of the wiring harness be the first area they check!! I'll bet if they bench test that sensor, it is just fine!! Ask them if the sensor was bench tested!!