The P1155 code in your 2023 Lexus GX indicates a problem with the air/fuel ratio sensor circuit on bank 2. This code signals an issue with the wide-band oxygen sensor on the side of the V6 opposite cylinder 1.
GX V6 Sensor Configuration
The GX's V6 engine has two banks, each with its own A/F ratio sensor before the catalytic converter. Bank 2 is typically the front bank (radiator side). P1155 indicates this sensor or its circuit has failed.
Common Causes of P1155
- Bank 2 A/F sensor failure
- Sensor heater circuit malfunction
- Wiring damage or corrosion
- Connector issues
- ECU circuit failure
- Exhaust leaks on bank 2
Symptoms of Bank 2 Sensor Issues
- Check engine light on
- Fuel economy decrease
- Performance reduction
- Rough running possible
- Emissions test failure
- Bank 2 running rich or lean
GX Off-Road Considerations
The GX is designed for off-road capability. Sensor wiring can be exposed to debris, water, and damage during trail use. Inspect connections if P1155 appears after off-road driving.