Check Engine Light trouble B3000

I have a 1999 B3000 and mechanics have given up on trying to get rid of my check engine light. They have replaced sensors (I'm not sure which), changed spark plugs and wires, and tuned up engine. It seems to run OK but the light comes back on after anywhere from a few blocks to a few miles. I've had a very good and reputable mechanic working on it. After three separate visits to his garage, he kept it for a week (determined to get to the bottom of the problem). He finally gave up, returned the truck to me and apologetically told me to take it to the dealer.
Any help or suggestions would be appreciated.

I had my light come on when i hit 130k on mine. But my Uncle is a big wig at a Mazda show here where i live so i get a tec to look at it and its just something that mazda puts in all there cars/trucks. It means you need to get it looked at by a Mazda Tec.


fun fun. my issue was my O2 senser.

disconnect the positive and negative battery terminals, touch them together for a second, then re-connect them. That will clear the computer memory. The code will come back if you haven't fixed the original problem.