Their location is as follows:
* One is located in the exhaust manifold, or very close to it, before the catalytic converter. This is the upstream sensor.
* The other is located in the exhaust pipe, after the catalytic converter. This is the downstream sensor.
However, to be absolutely certain, you should:
* Check your owner's manual: This is the best source for your specific vehicle's specifications.
* Look at a repair manual specific to your year and model: Chilton's or Haynes manuals often have diagrams showing sensor locations.
* Consult a parts store: Provide them with your VIN (Vehicle Identification Number), and they can look up the exact parts for your truck.
Without this verification, the above is just general information based on typical setups.
