I have a 98 V70 GLT. Check engine light came on and I took it to my mechanic. Vacuum leaks were found and fixed. No more check engine light. Took it for an I&M test the next day. It failed because "on board diagnostic system was not ready" (catalytic, evaporative, secondary air, oxygen sensor and oxygen sensor heater). That was a week ago. Have driven repeatedly since there, but the same code came when tried again on I&M. Took it to the dealer who said 98s have this problem with (not) resetting and they can do a forced reset for some $250, which could take 2 or 3 days of driving according to a particular protocol. They said this can/will happen whenever the battery is disconneted and for other reasons. This seems crazy. Any other options available?

 

Not sure. I have heard this in the threads several times. Maybe you can look in the S70 area and see what others have done.