The heated O2 sensor in bank 1 sensor 1 is giving a higher voltage reading than it should. For most vehicles the code comes when voltage exceeds 1.5V.
- Fuel temp is excessively high
- Short, open or broken wire in O2 sensor circuit
- Visually inspect all wiring to O2 sensor for loose, open or short connections
- Use a wiggle test to determine where the voltage drops out
- Using an OBD2 scanner, check whether sensor 1 of bank 1 is switching properly