* Upstream (before the catalytic converter): On the exhaust manifold, near the engine. This sensor is often closer to the engine's exhaust ports.
* Downstream (after the catalytic converter): On the exhaust pipe, after the catalytic converter. This one is further down the exhaust system.
To be absolutely certain:
1. Consult your owner's manual: The best place to find the precise location is your vehicle's owner's manual. It may have a diagram of the exhaust system.
2. Use a repair manual: A repair manual (like a Haynes or Chilton manual) specific to your year and model will have detailed diagrams and instructions.
3. Look online: Search for "[year] [make] [model] 3.8L oxygen sensor location" with images. You'll likely find pictures from other owners who have performed similar repairs.
Caution: The exhaust system gets extremely hot. Allow the engine to cool completely before attempting to locate the oxygen sensors.
