I bought my Tacoma used. Since I've gotten it, the catalytic converter, throttle body, air & fuel filters, belts and water pump have been replaced. It was running fine since then for about 2 months. Then the check engine light came on 2 weeks ago, but I reset it. This weekend, it came on again. I reset it and it came on again. I'm suspecting it might be faulty O2 sensors. It runs fine otherwise. Any ideas what else it might be? I'm going to get me an OBDII scanner to run my own diagnostics. Anyone have any idea where the connector port is located? It's a 2001 Tacoma V6.

the port is located under the dash where your right knee would be, you can't miss it.

Advanced auto will scan the code for free too. Advanced and Autozone.

I bought a scan tool and it came back with code P0171 - "System too lean bank 1". I spoke to a Toyota mechanic and he said it could have been anything from the mass air flow sensor to a vacuum leak to a bad O2 sensor to a bad fuel injector, etc. etc. So I called up my independent Honda mechanic and told him the problem. The Toyota Dealer's mechanic would have charged $98 just to plug in and diagnose what the trouble was, on top of the parts and labor and would probably have come out to $400 when all was said and done.

My independent Honda mechanic (I used to own a Honda and went to him for years) fixed it for $240. It was a faulty mass air flow sensor. He didn't even charge me for testing the O2 sensors and the vacuum leaks. Once that was replaced, the engine just purred. My fuel economy is better too and it's not bucking anymore either. I hate going to the dealer's mechanics; they charge too much and they suck. Every time I leave there, something else always goes wrong.