I've had my 2002 Milly for two years, got it with 141,000 miles and it now has about 162,000. It runs fine, gets about 21 1/2 mpg, but my check engine light goes on and off. It's on about 75% of the time, and when it's on both Auto Zone and my mechanic have said that the codes are for bad catalytic converters. I have no reason to believe that they are misreading the codes, but it confuses me that the light goes on and off. I have had the state mandated emissions inspection three times since I bought the car (they hook their computer up to the same place that Auto Zone and my mechanic have used), always when the CEL was off, and it's passed each time. Sometimes the light is off for as little as 60 miles, sometimes up to 250 miles. Then it will come back on for between 100 and 800 miles. I have usually done nothing to make it go off (except a couple of times when the battery had been disconnected or the codes had been cleared). It will not stay off for many miles after refuelling, and it seems like it has been off more often since I quit topping it up when I refuel. And it seems like it's more likely to go off after I've refueled without filling it all the way up. Does anybody have any thoughts on what's going on? I'd appreciate any input! Thanks!