On most Honda Odyssey models with the 3.5-liter V6, there are four O2 sensors: two upstream (before the catalytic converter) and two downstream (after the catalytic converter).
Overview of O2 sensors in the Odyssey
The Oxygen sensors monitor exhaust gas composition to help the engine manage fuel mix and emissions. In a typical Odyssey setup, Bank 1 Sensor 1 and Bank 2 Sensor 1 sit upstream of the catalytic converters, while Bank 1 Sensor 2 and Bank 2 Sensor 2 sit downstream of the converters. “Bank 1” generally refers to the exhaust bank containing cylinder 1 (on most Odyssey models this is the driver’s-side bank), and “Bank 2” is the opposite side. Exact placement can vary by year and engine variant, so it’s wise to verify against your specific model’s service documentation.
With that in mind, here are the common locations you’ll encounter on a standard 3.5L V6 Odyssey:
- Bank 1 Sensor 1 (B1S1) – upstream, located on or near the driver’s-side exhaust manifold port for the engine bank containing cylinder 1.
- Bank 2 Sensor 1 (B2S1) – upstream, located on the passenger’s-side exhaust manifold port for the other bank.
- Bank 1 Sensor 2 (B1S2) – downstream, located on the exhaust pipe after the catalytic converter on the driver’s-side bank.
- Bank 2 Sensor 2 (B2S2) – downstream, located on the exhaust pipe after the catalytic converter on the passenger’s-side bank.
When you’re inspecting or replacing sensors, look for the standard threaded fittings with electrical connectors and heat shields nearby. The sensors are coated in metal and have a wiring harness that runs toward the engine bay, usually clipped to the undercarriage or frame rails.
How to identify the exact sensors on your specific model
The following steps help you confirm which sensor is which on your particular Odyssey, especially if you’re dealing with a specific model year or trim level:
- Consult your vehicle’s service manual or official Honda diagrams for the exact sensor labeling (B1S1, B2S1, B1S2, B2S2).
- Safely raise and support the vehicle and locate the exhaust system along the underside; follow each exhaust pipe from the engine toward the rear to spot the sensors and their connectors.
- Identify upstream sensors by their placement closest to the engine on each exhaust bank; downstream sensors sit after the catalytic converters on the corresponding bank.
- Note the wiring harness routing and protective heat shielding; some models route sensors behind shields, requiring light removal or access panels.
If you’re unsure which sensor corresponds to which bank or position, check the VIN-specific schematics or ask a qualified technician. Different generations of the Odyssey can shift sensor placement slightly, and some models may have variations in the number of sensors due to catalytic converter design.
Variations by year and engine
While the four-sensor arrangement (two upstream, two downstream) is common for many Honda Odyssey 3.5L V6 configurations, older generations or different powertrains may differ in exact location or the number of sensors. Always verify against your exact model year and engine code (for example, J35A or its successors) using the owner’s manual, service manual, or a Honda dealer/authorized repair resource.
Summary
In most Honda Odyssey models with the 3.5L V6, you’ll find four O2 sensors: two upstream before the catalytic converters (B1S1 and B2S1) and two downstream after the converters (B1S2 and B2S2). Locations can vary slightly by year and engine, so use the vehicle’s manuals or a trusted diagram to confirm exact positions. Proper identification helps with diagnosis, replacement, and collision-free maintenance of the emissions control system.