I'm driving a 1992 240 wagon with about 170K on it. Last year in MA, I had trouble passing inspections and...after a new cat, o2 senser, and cleaning the combustion chamber...it passed with flying colors (HC=0.03gpm/limit=1.2, CO=0.18gpm/limit=20, NOx 0.02gpm/limit=2.5). However, the codes for the ECM wouldn't clear after a full reset.

Since then, we moved to CT and I'm back to the drawing board. After the 1st inspection, the NOx was almost double (2348 PPM/limit=1522) but all other emissions passed. After checking carefully for leaks on the air intake, I was leaning toward a faulty AMM so I replaced it. Thus far, it has corrected the codes on the ECM, but my second emission inspection didn't pass. In fact, the NOx went down a bit (1765 PPM) but the CO went up (0.71%/limit=0.70). Is it possible that a faulty AMM could ruin a new 02 sensor or catalytic converter??? Any thoughts are greatly appreciated!