You'll typically find:
* Upstream O2 sensors (pre-cat): These are located in the exhaust manifold or very close to it. There's usually one for each cylinder bank (so two total).
* Downstream O2 sensors (post-cat): These are located in the exhaust pipe after the catalytic converter(s). Again, there's usually one for each bank (two total).
To find them precisely:
1. Consult your vehicle's repair manual: This is the most accurate way to locate the sensors. The manual will have diagrams showing their precise location.
2. Use a repair database: Online resources like AllDataDIY or Mitchell 1 provide detailed diagrams and information for specific vehicle years and models. You'll need a subscription, but this is often more accessible than a physical repair manual.
3. Visual Inspection (with caution): With the engine cool, look under the vehicle near the exhaust manifolds and the catalytic converters. The O2 sensors are typically threaded into the exhaust system and have wiring harnesses connected to them. Be extremely careful when looking under the vehicle, as exhaust components get extremely hot.
Caution: The exhaust system components get very hot after the engine is run. Always let the engine cool completely before attempting any inspection or work under the vehicle.
