Please check fitment notes & description for accurate information.1999 Toyota 4Runner 2.7L1999-2000 Toyota 4Runner 3.4L2000 Toyota Tacoma 3.4L Oxygen Sensor's Location: How do I know the O2 sensor is good or not? Check engine light on A reduction in fuel economy. Your catalytic converter fails unexpectedly Exhaust emissions reach undesirable levels. .
