The upstream O2 sensor is reading a lean fuel mixture, this could be an O2 sensor, clogged injector, low fuel pressure.
I would replace the O2 sensor, erase code. If code reappears, then measure fuel pressure with mechanical gauge to start.
I would also add a can of SeaFoam after changing O2 sensor to gas tank.
Friday, January 15th, 2010 AT 10:06 AM