It's easy to retrieve the code and check out the reported problem yourself:
http://vbxmaxima.8m.com/ecu.html

Find another mechanic. He needs to read the code(s) and fix the
problem(s), not just reset the code.

Most of the problems indiciated by the MIL are minor emissions related
issues, like O2 sensors going bad, catalytic converter to doing its
thing etc. When there is a major issue, the MIL blinks, but then it is
not as if you would need the blinking MIL to tell you that there is a
major problem like cylinder mis-firing. That would be very noticeable
without the MIL. Anyway, it's easy to diagnose, as someone pointed to
the link at vbmaxima.

CD