How many O2 sensors does a Lexus ES330 have?
The Lexus ES330 uses four oxygen sensors in its exhaust system—two upstream sensors before the catalytic converters and two downstream sensors after them. This configuration applies to U.S.-spec ES330 models produced around 2004–2006 with the 3.3L V6 engine (3MZ-FE).
Sensor layout and purpose
Oxygen sensors monitor exhaust oxygen content to help the engine control unit optimize fuel mixture and to assess catalytic converter performance. In a V6 ES330, a twin-bank exhaust arrangement requires sensors on each bank to accurately measure before and after the catalysts.
Locations and counts
Key facts about the O2 sensor layout are summarized below.
- Upstream (pre-cat) oxygen sensors: two sensors, one for each bank, located before the catalytic converters.
- Downstream (post-cat) oxygen sensors: two sensors, one after each catalytic converter, located downstream of the catalysts.
In total, the ES330 uses four O2 sensors. This arrangement supports real-time fuel trim adjustments and proper catalyst monitoring, contributing to emissions compliance and smooth drivability.
Maintenance considerations
Regular inspection of O2 sensors is recommended if you notice engine misfires, reduced fuel economy, rough idle, or a check engine light. Replacement should follow the manufacturer's specifications and OBD-II diagnostic codes. Using OEM or quality aftermarket sensors helps ensure compatibility with the ES330's engine control system.
Summary
Short answer: Four O2 sensors. The ES330 employs two upstream sensors and two downstream sensors—one pair on each bank—totaling four sensors to monitor exhaust gases and catalyst performance.
