The two catalytic converters.
In the 2004 Honda Accord V6, the exhaust system uses two catalytic converters—one for each bank of the V6 engine—positioned along the exhaust path between the headers and the muffler. This arrangement helps meet emissions standards and ensures pollutants from both banks are treated before the exhaust leaves the vehicle.
Exhaust layout and the two converters
Understand how the two converters fit into the overall exhaust system:
- Two catalytic converters in total — one on each bank of the V6 engine.
- Each converter is placed along its bank's exhaust path, typically between the manifold and the shared downpipe.
- Oxygen sensors: usually two upstream sensors (before the converters) and two downstream sensors (after the converters) to monitor performance.
- The two converters feed into a common pipe that eventually leads to the resonator and muffler.
Note that exact layout can vary by market or trim; some regional versions may differ slightly, but two catalytic converters are standard for most 2004 U.S.-market Accord V6 models.
Maintenance and replacement considerations
When assessing or replacing components, keep these points in mind:
- If you replace a converter, you will likely need to replace or recalibrate associated oxygen sensors and check engine codes.
- Replacing both converters is common in one service if both have failed or show excessive deterioration.
- Use OEM or equivalent high-quality catalytic converters to maintain emission compliance and avoid future failure codes.
- Be aware of regional emissions requirements; California, for example, has stricter standards that influence part specifications and testing.
For most owners, understanding there are two cats helps explain why repairs can be more involved and potentially more costly than a single-cat design.
Summary
The 2004 Honda Accord V6 typically uses two catalytic converters—one for each bank of the engine—arranged in series along the exhaust path before the muffler. This setup supports emissions compliance and efficient pollutant reduction, with sensors monitoring performance on both banks. If you're planning maintenance or replacement, expect to address both converters and related sensors as a system.