P1151: Definitions depend on the manufacturer — what it means, the affected system and what to check before replacing parts.
Lack Of HO2S21 Switch - Sensor Indicates Lean. Source catalogue definition; confirm applicability using vehicle service information.
Affected system: Powertrain
Also written as: P1151-00, P115100 (some scan tools add the fault-type byte, e.g. -00).