Where is the bank 1 sensor 2 on a Lexus IS250?
The Bank 1 Sensor 2 on a Lexus IS250 is the downstream oxygen sensor for the bank that contains cylinder 1, located after the catalytic converter along the exhaust downpipe on that bank.
What Bank 1 Sensor 2 means for your IS250
In a typical Lexus V6 setup, each exhaust bank has two O2 sensors: Sensor 1 sits upstream (before the catalytic converter) and Sensor 2 sits downstream (after the catalytic converter). Bank 1 refers to the bank that includes cylinder 1. Therefore, Bank 1 Sensor 2 is the post-cat oxygen sensor on the Bank 1 side. This sensor helps monitor catalytic efficiency and informs fuel trim adjustments via the engine control module.
Note: Some model years or regional variants may route sensors slightly differently. Always consult the factory service manual or a trusted repair guide for your exact VIN to confirm location and torque specs.
Where to locate Bank 1 Sensor 2 on the IS250
Access typically requires safely lifting the vehicle and inspecting the exhaust downpipe on the bank that contains cylinder 1. Bank 1 Sensor 2 is mounted downstream of the catalytic converter and connects via a multi-wire harness that runs along the underside of the car. On many US-spec IS250s, this sensor sits along the passenger-side exhaust pipe toward the rear of the catalytic converter, making it reachable from underneath the vehicle.
Before you begin, ensure the engine and exhaust are cool and have the proper tools ready. Disconnecting the battery is a prudent safety step when working near electrical connectors.
Steps to locate the sensor
- Raise and secure the vehicle on jack stands and allow the exhaust to cool.
- Identify the catalytic converter on the exhaust downpipe associated with Bank 1 (the bank that includes cylinder 1).
- Follow the exhaust pipe downstream from the cat until you find the oxygen sensor with a multi-wire harness; this is Bank 1 Sensor 2.
- Verify the sensor by its position relative to the cat and, if available, cross-check the connector type with the service manual.
Keep in mind that wiring colors and sensor housings can vary slightly by year and market. If in doubt, refer to the official repair guide for your IS250’s exact configuration.
Tips for replacement and testing
When replacing Bank 1 Sensor 2, choose an OEM or equivalent sensor and follow proper installation torque. After installation, clear any codes and run the engine to operating temperature to observe sensor readings with a diagnostic tool. Compare downstream (Bank 1 Sensor 2) readings against upstream sensors and the second bank to assess catalytic efficiency and overall sensor health.
Summary: Bank 1 Sensor 2 is the downstream oxygen sensor for the IS250’s Bank 1, located on the exhaust downpipe after the catalytic converter. It is generally accessible from underneath the vehicle on the bank-side that contains cylinder 1; always verify exact location using your vehicle’s service manual for year-specific routing and specs.
