A/F Sensor Circuit Range/Performance (Bank 1 Sensor 1).
This is a malfunction of O2 or Fuel/Air ratio sensor. Find out what type of sensor you have and replace it. IF you have a California-emissions car, you probably have an A/F ratio sensor. Other cars usually have an O2 sensor. Better make sure though.
If you have a V6, the heated O2 sensor Bank 1 Sensor 1 is on the right hand exhaust manifold (rear firewall side). 4cyl is front near radiator.
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