The dealer "fibbed". The generic OBDII readers do work, but they will not give you Volvo specific codes. When the Autozone guys read the codes and translated one as a mass air leak, that didn't mean there was a problem with the MAF. It meant that the throttle body was getting more air than the MAF was registering, which means that there may be a leak in the hose going from the MAF to the throttle body. That error is generated because the first O2 sensor is detecting a lean burn rate, probably due to too much air coming in.

The dealer should have given you a list of the other codes, with definitions and solutions. A lot of codes may be stored without triggering any CEL because they only occured once. The dealer should have been able to tell you which one caused the CEL to turn on.

Did you tell Autozone to clear the codes after they read them to you? Remember, the generic code readers normally only catch engine and tranny faults, not faults from other areas like the ECC, instrument panel, air bags, electric seats, etc.

Klaus
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(V♂LV♂s 1995 854T, 1998 V70R)