P1157 — Lack Of HO2S21 Switch - Sensor Indicates Rich

What it means

P1157 is an OBD-II diagnostic trouble code: Lack Of HO2S21 Switch - Sensor Indicates Rich.

Typical fix

Confirm the code with an OBD-II scanner, then inspect the component or circuit named above. Consult a vehicle-specific service manual for the full diagnostic and repair procedure.