I have a 1996 Nissan Maxima. Back on 8/19/09 I had my muffler replaced. In addition my emissions light was stuck on. as well as my air bag light. Below is what is written on my repair invoice.

scanned computer, found codes. PO325 knock sensor problem (bank 1) and P0136-o2 sensor (B1S2) Erased these on 8/19/09. On 9/3 there were no codes to actually set, but 325 was pending and several readiness monitors had not reset. We erased air bag light.

Failed Inspection (MA) resident: Below is the inspection failure report

Catalyst monitor NOT ready
Catalyst heater monitor-NOT supported
Evaporative System monitor Ready
Secondary air system monitor NOT supported
a/c system monitor NOT supported
O2 Sensor monitor NOT ready
O2 sensor heater monitor ready
Exhaust Gas recirculation monitor NOT ready

I drove about 800 miles and went back for inspection and the exact same failed emissions report printed. Drove another 600 miles went back still failed same reasons.

I'm running out of time so I hoping someone can help me. I should mention that the mechanic I have used for several years is an "authorized emissions garage". MA law states that your car has to be brought to one of the specialized emissions garages. Really can't afford a $700 bill.