In most Honda Pilot models with the 3.5-liter V6, there are four oxygen sensors: two upstream (before the catalytic converter) and two downstream (after it), one pair on each exhaust bank. They are mounted on the exhaust manifolds and along the exhaust pipe near the engine and undercarriage.
Understanding their placement helps with diagnostics, maintenance, and replacement. The basic layout—two banks with one up and one down sensor per bank—remains consistent, though exact wiring routes can vary by year and trim. When in doubt, consult the factory manual for your specific year and engine code.
Sensor layout on the Honda Pilot
In a typical Honda Pilot with the V6 engine, exhaust gases flow from the two banks into the catalytic converters, and sensors monitor oxygen content before and after the cat to optimize the air-fuel ratio and monitor catalytic efficiency.
Here is a quick reference to the sensor designations and their approximate locations on the exhaust system:
- Bank 1 Sensor 1 (B1S1): Upstream sensor located on the Bank 1 exhaust manifold/collector, before the catalytic converter.
- Bank 1 Sensor 2 (B1S2): Downstream sensor located on Bank 1 after the catalytic converter along the exhaust pipe.
- Bank 2 Sensor 1 (B2S1): Upstream sensor located on the Bank 2 exhaust manifold/collector, before the catalytic converter.
- Bank 2 Sensor 2 (B2S2): Downstream sensor located on Bank 2 after the catalytic converter along the exhaust pipe.
Note: Sensor numbering can vary slightly by year or service manual; the important idea is that there are two upstream sensors and two downstream sensors, one on each exhaust bank.
Practical tips for locating them on your car
To locate the sensors on your specific vehicle, look for the following clues:
- The sensors are cylindrical metal probes with a wiring harness entering a protected plastic connector.
- Upstream sensors are the ones closest to the engine on each bank; downstream sensors are further back, near or after the catalytic converter.
- On most models, you’ll find them along the exhaust manifold/collector area and the pipe section just after the catalytic converter, before the exhaust resonator/muffler.
Concluding information: If you are replacing or testing O2 sensors, ensure you disconnect the battery before working near the exhaust wiring, wait for the system to cool, and use anti-seize on the sensor threads as recommended by the service manual. If you suspect a faulty O2 sensor, use an OBD-II scanner to check live sensor data or consult a professional mechanic.
Summary
The Honda Pilot typically uses four O2 sensors—two upstream and two downstream—mounted on both exhaust banks. They are located at the exhaust manifolds and the pipes after the catalytic converters. For exact placement and wiring for your year and trim, refer to the owner’s manual or a year-specific repair guide.