We have a 1994 850 turbo sedan. It has a fault read out module on top of the engine. Always before we could read the faults and then clear the codes. We can't get the codes to clear anymore.. Do these modules go bad often.?. We know the dealer reads the faults from under the dash.Is it possible for the dealer to clear codes from under the dash without clearing the module? The reason we ask is that we have a check engine light on and it read the codes for front knock sensor. Also code for drivers side interior temp. sensor inlet fan seized. These are the same codes it read out when the dealer fixed it. We had the dealer replace the front knock sensor 1 1/2 year ago. hurtful expense. Can't believe that it would go out again so fast.. We have only gone 2000 miles in that time due to high gas prices. Would appreciate any ideas?? Not too happy with the Volvo dealer here..Lyle Pearson..