The quick takeaway: two O2 sensors on the four-cylinder models, four on the V6 models. The exact count depends on the engine configuration installed in your car.
The 2002 Accord offered two engines: a 2.3-liter inline-four and a 3.0-liter V6. Because of the different exhaust layouts, each engine type uses a different O2 sensor count.
Four-cylinder engine (2.3L)
Two sensors are typically installed: one upstream before the catalytic converter and one downstream after the catalytic converter.
- Upstream O2 sensor (pre-cat) — measures exhaust before the catalytic converter.
- Downstream O2 sensor (post-cat) — monitors catalytic converter efficiency after the catalytic converter.
In four-cylinder Accords, these two sensors monitor both fuel mixture and catalytic converter performance.
V6 engine (3.0L)
The V6 configuration uses four sensors: two upstream sensors (one for each bank) and two downstream sensors (one for each bank).
- Upstream sensor Bank 1 (pre-cat) — measures exhaust before the catalytic converter on bank 1.
- Downstream sensor Bank 1 (post-cat) — monitors catalytic converter efficiency on bank 1.
- Upstream sensor Bank 2 (pre-cat) — measures exhaust before the catalytic converter on bank 2.
- Downstream sensor Bank 2 (post-cat) — monitors catalytic converter efficiency on bank 2.
For the V6 configuration, you should expect two upstream sensors and two downstream sensors corresponding to the dual-bank exhaust setup.
Summary
In summary, a 2002 Honda Accord with a 2.3L four-cylinder typically has 2 O2 sensors, while the 3.0L V6 version uses 4 sensors. If you’re diagnosing or ordering replacements, verify the engine code or check under the hood to confirm which engine your car has, as this determines the sensor count and locations.